- 1-Naphthylmethyl and 1-naphthylmethoxymethyl protecting groups: New members of the benzyl- and benzyloxymethyl-type family
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1-Naphthylmethyl (NAPI) and 1-naphthylmethoxymethyl (NAPOMI) protecting groups were developed as new members of the benzyl- and benzyloxymethyl-type family. NAPI and NAPOMI can be introduced under conventional conditions, such as NAPIBr/NaH/room temperature (rt), or NAPOMICl/i-Pr2EtN/rt. They can also be removed under conventional conditions, e.g., by dichlorodicyanobenzoquinone (DDQ)- or ceric ammonium nitrate (CAN)-mediated oxidation, or by hydrogenolysis. The specific advantages of these new protecting groups are: i) a less costly synthesis of NAPOMICl compared to NAPOMIICl, ii) the possibility to remove NAPOMII selectively in the presence of NAPOMI by DDQ-mediated oxidation, and iii) the compatibility with strong acids even in the presence of hard nucleophiles.
- Sato, Takuya,Joh, Yohei,Oishi, Tohru,Torikai, Kohei
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- THE IN SITU PROTECTION OF ALDEHYDES VIA α-AMINO ALKOXIDES
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Aromatic and aliphatic aldehydes can be protected in situ via the formation of α-amino alkoxides and their O-trimethylsilyl derivatives.
- Comins, Daniel L.,Brown, Jack D.
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- 81. Loss of H2O from M + t-Butyl Complex Ions of Benzyl Alcohol in Isobutane Chemical Ionization Mass Spectrometry
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In isobutane chemical ionization mass spectrometry benzyl alcohol exhibits ions at m/z 147 ('M +39') that arise by a loss of H2O from +, i.e. 'M + 57' complex ions.Electrophilic aromatic substitution of a proton at an ortho-position of neutral C6H5CH2OH with + and, alternatively, nucleophilic substitution of H2O at the benzylic carbon in C6H5CH2O+H2 with CH2=C(CH3)2 are discussed as possible pathways.Evidence in favor of the latter is derived from the analysis of C6D5CH2OH and C6H5CD2OH for the origin of the H-atoms lost in H2O.The inferred ion structure of m/z 147 is verified by mass-analyzed ion kinetic energy (MIKE.) measurements of its collision- activated (CA.) decomposition.MIKE./CA. spectra of mass-selected m/z 147 ions, once generated by CI(i-C4H10) from benzyl alcohol and, once, from 2-methyl-4-phenyl-2-butanol match closely and, thus, reflect identical ion structures.With reference to the simple genesis of this ion from the latter precursor, the structure in question can be concluded to be C6H5CH2CH2C+(CH3)2.
- Liehr, Joachim G.,Brenton, Gareth A.,Beynon, John H.,McCloskey, James A.,Blum, Wolfgang,Richter, Wilhelm J.
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- PHOTOLYSIS OF 2-PHENYLETHYL AND 4-PHENYL-1-BUTYL HALIDES IN ALCOHOLIC SOLVENTS
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Photolysis of 2-phenylethyl bromide in the lower alcohols gave the corresponding carbinols and ethers as the main products.With 2-phenylethyl iodide, the products were almost exclusively of the latter type, while 4-phenyl-1-butyl halides gave n-butylbenzene, 4-phenyl-1-butene and tetralin.It is shown that each of these products may be assigned to an ionic or radical pathway and that both the nature of the sovent and the structure of the substrate affect the course of photolysis.There is a substrate dependent preference for specific reactions along pathways of both the radical and ionic types.The variations in product composition and distribution are rationalized in terms of the relative efficiencies furnished in these pathways for the relaxation of high energy intermediates produced in the initial stages of photolysis.Intervention by the phenyl group is more pronunced in the case of 2-phenylethyl halides than in the case of the higher homologues and more effective in the ionic pathway.
- Bhalerao, V. K.,Nanjundiah, B. S.,Sonawane, H. R.,Nair, P. M.
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- 2-Naphthylmethoxymethyl as a Mildly Introducible and Oxidatively Removable Benzyloxymethyl-Type Protecting Group
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2-Naphthylmethoxymethyl (NAPOM) was developed for the protection of various hydroxy (including phenolic hydroxy and carboxy) and mercapto groups. The NAPOM group can be introduced in extremely mild conditions (naphthylmethoxymethyl chloride, 2,6-lutidine, room temperature) without concomitant acyl migration in a 1,2-diol system. Furthermore, selective removal of NAPOM in the presence of naphthylmethyl (NAP) and p-methoxybenzyl (PMB) groups and, conversely, that of PMB in the presence of NAPOM were realized. These results, as well as its easy handling and compatibility with various solvents, show that NAPOM is a novel and useful choice as a protecting group.
- Sato, Takuya,Oishi, Tohru,Torikai, Kohei
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- Synthesis and evaluation of 1,1,7,7-tetramethyl-9-azajulolidine (TMAJ) as a highly active derivative of N,N-dimethylaminopyridine
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1,1,7,7-Tetramethyl-9-azajulolidine (TMAJ), which theoretical studies have suggested as a highly active DMAP analog, was synthesized for the first time. The catalytic activity of TMAJ was confirmed by the acetylation reactions of various tert-alcohols. TMAJ showed much higher catalytic activity than DMAP and one of the highest activity levels among the conventional DMAP analogs. These experimental results were in good agreement with the previous theoretical studies.
- Tsutsumi, Tomohiro,Saitoh, Arisa,Kasai, Tomoyo,Chu, MengYue,Karanjit, Sangita,Nakayama, Atsushi,Namba, Kosuke
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- A mild and feasible deprotection of alcohol tetrahydropyranyl or methoxymethyl ethers catalyzed by Sc(OTf)3
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Tetrahydropyranyl or methoxymethyl ethers can be easily deprotected by treatment of a catalytic amount of scandium trifluoromethanesulfonate along with methanol or 1,3-propanediol, respectively, to afford the corresponding parent alcohols in high to excellent yields.
- Oriyama,Watahiki,Kobayashi,Hirano,Suzuki
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- Synergistic Catalysis for the Umpolung Trifluoromethylthiolation of Tertiary Ethers
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The first transition-metal-free, site-specific umpolung trifluoromethylthiolation of tertiary alkyl ethers has been developed, achieving the challenging tertiary C(sp3)–SCF3 coupling under redox-neutral conditions. The synergism of organophotocatalyst 4CzIPN and BINOL-based phosphorothiols can site-selectively cleave tertiary sp3 C(sp3)–O ether bonds in complex molecules initiated by a polarity-matching hydrogen-atom-transfer (HAT) event. The incorporation of several competing benzylic and methine C(sp3)?H bonds in alkyl ethers has little influence on the regioselectivity. Selective difluoromethylthiolation of C?O bonds has also been achieved. This represents not only an important step forward in trifluoromethylthiolation but also a promising means for site-selective C?O bond functionalization of unsymmetrical tertiary alkyl ethers.
- Xu, Wentao,Ma, Junyang,Yuan, Xiang-Ai,Dai, Jie,Xie, Jin,Zhu, Chengjian
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- Reaction of methylcerium reagent with tertiary amides: Synthesis of saturated and unsaturated ketones from tertiary amides
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The reaction of CeCl3-MeLi to tertiary amides has been studied. The reagent prepared from cerium(III) chloride and methyllithium at 0°C adds cleanly to morpholine amides to give the corresponding methyl ketones. Even in the presence of a large excess of the reagent, no tertiary alcohol formation is observed, indicating that the tetrahedral intermediates are stable under the reaction conditions employed.
- Kurosu, Michio,Kishi, Yoshito
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- Electrocatalytic Oxidative Hydrofunctionalization Reactions of Alkenes via Co(II/III/IV) Cycle
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Here we disclose a general Co(II/III/IV) electrocatalytic platform for alkene functionalization. Driven by electricity, a set of the oxidative hydrofunctionalization reactions via hydrogen atom transfer were demonstrated without the need for stochiometric chemical oxidants. The scope of the reactions encompasses hydroalkoxylation, hydroacyloxylation, hydroarylation, semipinacol rearrangement, and deallylation. Mechanistic studies and stereochemical evidence support an ECEC process involving an electrochemically generated organocobalt(IV) intermediate. This work presents an example of reactivity space expansion in electrocatalysis in the VB12-system by going beyond the common oxidation states of Co(I/II/III).
- Yang, Fan,Nie, Yi-Chen,Liu, Han-Yuan,Zhang, Lei,Mo, Fanyang,Zhu, Rong
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p. 2132 - 2137
(2022/02/10)
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- Umpolung Strategy for Arene C?H Etherification Leading to Functionalized Chromanes Enabled by I(III) N-Ligated Hypervalent Iodine Reagents
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The direct formation of aryl C?O bonds via the intramolecular dehydrogenative coupling of a C?H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C?H etherification via an umpoled alcohol cyclization mediated by an I(III) N-HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization-iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O-intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2-shift pathways. (Figure presented.).
- Mikhael, Myriam,Guo, Wentao,Tantillo, Dean J.,Wengryniuk, Sarah E.
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supporting information
p. 4867 - 4875
(2021/09/14)
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- Nickel-Catalyzed Hydrodeoxygenation of Aryl Sulfamates with Alcohols as Mild Reducing Agents
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The nickel-catalyzed hydrodeoxygenation of aryl sulfamates has been developed with alcohols as mild reductants. A variety of functional groups and heterocycles were tolerated in this reaction system to give the desired products in high yields. In addition, the gram-scale process and stepwise cine-substitution were also achieved with high efficiency.
- Matsuo, Kasumi,Kuriyama, Masami,Yamamoto, Kosuke,Demizu, Yosuke,Nishida, Koyo,Onomura, Osamu
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p. 4449 - 4460
(2021/08/25)
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- Cu-catalyzed cross-coupling of benzylboronic esters and epoxides
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A reaction between epoxides and benzylboronic acid pinacol esters is described. CuI was found to be an effective catalyst of this transformation upon activation of the benzylboronic ester with an alkyllithium reagent. The reaction was very efficient and a variety of substituted epoxides were found to be good substrates with good regioselectivity for substitution at the less substituted side of the epoxide. A reaction using an enantioenriched secondary benzylboronic ester was found to not be stereospecific.
- Gierszal, Sophia G.,Barker, Timothy J.
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supporting information
(2021/09/20)
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- Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
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The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
- Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
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supporting information
p. 5486 - 5490
(2020/07/24)
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- Design, synthesis and biological evaluation of 8-(2-amino-1-hydroxyethyl)-6-hydroxy-1,4-benzoxazine-3(4H)-one derivatives as potent β2-adrenoceptor agonists
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A series of β2-adrenoceptor agonists with an 8-(2-amino-1-hydroxyethyl)-6-hydroxy-1,4-benzoxazine-3(4H)-one moiety is presented. The stimulatory effects of the compounds on human β2-adrenoceptor and β1-adrenoceptor were characterized by a cell-based assay. Their smooth muscle relaxant activities were tested on isolated guinea pig trachea. Most of the compounds were found to be potent and selective agonists of the β2-adrenoceptor. One of the compounds, (R)-18c, possessed a strong β2-adrenoceptor agonistic effect with an EC50 value of 24 pM. It produced a full and potent airway smooth muscle relaxant effect same as olodaterol. Its onset of action was 3.5 min and its duration of action was more than 12 h in an in vitro guinea pig trachea model of bronchodilation. These results suggest that (R)-18c is a potential candidate for long-acting β2-AR agonists.
- Yi, Ce,Xing, Gang,Wang, Siqi,Li, Xiaoran,Liu, Yichuang,Li, Jinyan,Lin, Bin,Woo, Anthony Yiu-Ho,Zhang, Yuyang,Pan, Li,Cheng, Maosheng
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- Controllable Intramolecular Unactivated C(sp3)-H Amination and Oxygenation of Carbamates
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Dual catalyst-controlled intramolecular unactivated C(sp3)-H amination and oxygenation of carbamates merging visible-light photocatalysis and earth-abundant transition metal catalysis have been reported. Useful amino alcohol and diol derivatives could be selectively obtained from readily available tertiary alcohol derivatives. The possible mechanisms have been proposed via a 1,5-HAT process followed by Lewis acid-controlled cyclization. The nickel and zinc catalysts inhibit the formation of oxygenation and amination products, respectively. An interesting phenomenon of chirality transfer is also observed.
- Guo, Qihang,Ren, Xiang,Lu, Zhan
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supporting information
p. 880 - 884
(2019/05/16)
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- Design, synthesis and biological evaluation of 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one derivatives as potent β2-adrenoceptor agonists
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A series of novel β2-adrenoceptor agonists with a 5-(2-amino-1-hydroxyethyl)-8-hydroxyquinolin-2(1H)-one moiety was designed, synthesized and evaluated for biological activity in human embryonic kidney 293 cells and isolated guinea pig trachea. Compounds 9g and (R)-18c exhibited the most excellent β2-adrenoceptor agonistic effects and high β2/β1-selectivity with EC50 values of 36 pM for 9g and 21 pM for (R)-18c. They produced potent airway smooth muscle relaxant effects with fast onset of action and long duration of action in an in vitro guinea pig trachea model of bronchodilation. These results support further development of the two compounds into drug candidates.
- Xing, Gang,Pan, Li,Yi, Ce,Li, Xiaoran,Ge, Xinyue,Zhao, Ying,Liu, Yichuang,Li, Jinyan,Woo, Anthony,Lin, Bin,Zhang, Yuyang,Cheng, Maosheng
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p. 2306 - 2314
(2018/11/06)
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- Light-Mediated Formal Radical Deoxyfluorination of Tertiary Alcohols through Selective Single-Electron Oxidation with TEDA2+.
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The synthesis of tertiary alkyl fluorides through a formal radical deoxyfluorination process is described herein. This light-mediated, catalyst-free methodology is fast and broadly applicable allowing for the preparation of C?F bonds from (hetero)benzylic, propargylic, and non-activated tertiary alcohol derivatives. Preliminary mechanistic studies support that the key step of the reaction is the single-electron oxidation of cesium oxalates—which are readily available from the corresponding tertiary alcohols—with in situ generated TEDA2+. (TEDA: N-(chloromethyl)triethylenediamine), a radical cation derived from Selectfluor.
- Aguilar Troyano, Francisco José,Ballaschk, Frederic,Jaschinski, Marcel,?zkaya, Yasemin,Gómez-Suárez, Adrián
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supporting information
p. 14054 - 14058
(2019/11/11)
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- Practical Intermolecular Hydroarylation of Diverse Alkenes via Reductive Heck Coupling
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The hydroarylation of alkenes is an attractive approach to construct carbon-carbon (C-C) bonds from abundant and structurally diverse starting materials. Herein we report a palladium-catalyzed reductive Heck hydroarylation of aliphatic and heteroatom-substituted terminal alkenes and select internal alkenes with an array of (hetero)aryl iodides. The reaction is anti-Markovnikov selective with terminal alkenes and tolerates a wide variety of functional groups on both the alkene and (hetero)aryl coupling partners. Additionally, applications of this method to complex molecule diversifications are demonstrated. Mechanistic experiments are consistent with a mechanism in which the key alkylpalladium(II) intermediate is intercepted with formate and undergoes a decarboxylation/C-H reductive elimination cascade to afford the saturated product and turn over the cycle.
- Gurak, John A.,Engle, Keary M.
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p. 8987 - 8992
(2018/09/11)
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- AGENT FOR INTRODUCING PROTECTING GROUP FOR HYDROXY GROUP AND/OR MERCAPTO GROUP
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A novel agent for introducing a protecting group for a hydroxy group and/or a mercapto group that can be introduced and removed under mild conditions is provided. The agent for introducing a protecting group for a hydroxy group and/or mercapto group of a substrate compound having the hydroxy group and/or mercapto group is represented by the following formula (I), wherein A represents a ring structure having 1 to 5 rings in which two carbon atoms of an adjacent benzene ring are included, the ring structure comprises a substituted or unsubstituted five-membered ring or six-membered ring and optionally include a heterocycle; each of R1, R2, R3, and R4 is independently a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; and X is a halogen atom or OSO2R5 (R5=an aryl group or an alkyl group).
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Paragraph 0055; 0556
(2017/11/11)
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- Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
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The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
- Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
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supporting information
p. 6592 - 6603
(2017/07/15)
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- E-selective semi-hydrogenation of alkynes with dinuclear iridium complexes under atmospheric pressure of hydrogen
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Semi-hydrogenation of alkynes was catalyzed by halide-bridged dinuclear iridium complexes, yielding (E)-alkenes with high selectivity. Mechanistic studies conducted with monohydride dinuclear species, dihydride mononuclear species, and trihydride dinuclear species led us to propose a mechanism involving dual cycles.
- Higashida, Kosuke,Mashima, Kazushi
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supporting information
p. 866 - 868
(2016/08/13)
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- PROCESS FOR PREPARING 4-CYCLOHEXYL-2-METHYL-2-BUTANOL
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The present invention relates to a process for preparing 4-cyclohexyl-2-methyl-2-butanol. The process comprises the following steps: a) reaction of styrene with isopropanol at elevated temperature to obtain 4-phenyl-2-methyl-2-butanol, andb) heterogeneously catalyzed hydrogenation of 4-phenyl-2-methyl-2-butanol over a catalyst suitable for ring hydrogenation of aromatics.
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Paragraph 0121-0123
(2015/09/22)
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- Amines vs. N-Oxides as Organocatalysts for Acylation, Sulfonylation and Silylation of Alcohols: 1-Methylimidazole N-Oxide as an Efficient Catalyst for Silylation of Tertiary Alcohols
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A comparison of the relative catalytic efficiencies of Lewis-basic amines vs. N-oxides for the acylation, sulfonylation and silylation of primary, secondary and tertiary alcohols is reported. Whilst the amines are generally superior to the N-oxides for acylation, the N-oxides are superior for sulfonylation and silylation. In particular, 1-methylimidazole N-oxide (NMI-O) is found to be a highly efficient catalyst for sulfonylation and silylation reactions. To the best of our knowledge, NMI-O is the first amine or N-oxide Lewis basic organocatalyst capable of promoting the efficient silylation of tert-alcohols in high yield with low catalyst loading under mild reaction conditions.
- Murray, James I.,Spivey, Alan C.
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supporting information
p. 3825 - 3830
(2016/01/25)
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- METHOD FOR PRODUCING ALKYL GRIGNARD REAGENT USING 4-METHYLTETRAHYDROPYRAN AS SOLVENT
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PROBLEM TO BE SOLVED: To solve the problems in the production of a Grignard reagent by using an alkyl iodide compound and magnesium. SOLUTION: There is provided a method for producing a Grignard reagent represented by the following formula (2), RMgI (2) by reacting an alkyl iodide compound represented by the following formula (1), RI (1) (where, R represents a methyl group or an ethyl group) and magnesium in 4-methyltetrahydropyran. According to the present invention, a Grignard reagent can be easily produced, the cost of apparatus and equipment can be reduced and the reaction operation in the subsequent process can be simplified. Further, since 4-methyltetrahydropyran as a solvent can be reused, the amount used of the solvent can be reduced. COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0033; 0034
(2018/11/22)
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- 2-methyl-4-phenyl-2-ol manufacturing method
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The invention relates to a method for preparing 2-Methyl-4-phenylbutan-2-ol by reacting a benzylmagnesium halide with isobutylene oxide. 2-Methyl-4-phenylbutan-2-ol can be used as an odorant.
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Paragraph 0028; 0029
(2016/12/22)
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- PROCESS FOR PRODUCING 4-CYCLOHEXYL-2-METHYL-2-BUTANOL
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The present invention relates to the field of perfumery. More particularly, it concerns a process for the preparation of 2-methyl-4-phenyl-2-butanol, or even 4-cyclohexyl-2-methyl-2-butanol from 4,4-dimethyl-2,6-diphenyl-1,3-dioxane.
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- METHOD FOR PREPARING 2-METHYL-4-PHENYLBUTAN-2-OL
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For the preparation of 2-methyl-4-phenylbutan-2-ol, a benzylmagnesium halide is reacted with isobutylene oxide. 2-Methyl-4-phenylbutan-2-ol is suitable as a fragrance.
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Paragraph 0027
(2014/03/25)
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- PROCESS FOR PREPARING 4-CYCLOHEXYL-2-METHYL-2-BUTANOL
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A process for preparing 4-cyclohexyl-2-methyl-2-butanol, comprising: a) reaction of styrene with isopropanol at elevated temperature to obtain 2-methyl-4-phenyl-2-butanol, andb) heterogeneously catalyzed hydrogenation of 2-methyl-4-phenyl-2-butanol over a catalyst suitable for ring hydrogenation of aromatics, where the molar ratio of the styrene used in step a) to the isopropanol used in step a) is in the range from 1:below 5 to 1:0.5.
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Paragraph 0105; 0107
(2013/03/28)
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- A family of stilbene-ethers as photolabile protecting groups for primary alcohols offers controlled deprotection based on choice of wavelength
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A novel stilbene-ether type of photolabile protecting group (PPG) for hydroxyl group has been developed. It contains a stable aryl ether group in the protected form and can be deprotected by acid-catalyzed photorearrangement under 300-nm irradiation. The selective deprotection has also been achieved by irradiation of the mixture of 4-alkoxystilbene and 2-(4-alkoxystyryl)furan at 365 nm.
- Ho, Jinn-Hsuan,Lee, Ya-Wen,Chen, Ying-Zhe,Chen, Pin-Sian,Liu, Wei-Qi,Ding, Yi-Shun
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p. 7325 - 7332
(2013/08/23)
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- The convenient and useful esterification of bulky tertiary alcohols using strontium compounds
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Various esters reacted with metallic strontium and alkyl iodides to give dialkylated products, followed by adding acid chlorides or acid anhydrides to afford the corresponding bulky tert-alcohol esters in good yields.
- Miyoshi, Norikazu,Asaoka, Masashi,Miyazaki, Yasuaki,Tajima, Takahiro,Kikuchi, Makoto,Wada, Makoto
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scheme or table
p. 35 - 36
(2012/03/13)
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- Strecker-type reaction of nitrones using cyanohydrin
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Strecker-type reaction of nitrones using acetone cyanohydrin as a cyanide source was developed. By treating nitrones with acetone cyanohydrin in the presence of n-BuMgCl, transcyanation from the cyanohydrin to the nitrones smoothly proceeded in THF at 35 °C. The amount of n-BuMgCl could be reduced to 0.2 equiv to give the corresponding α-cyanohydroxylamines in up to 98% yields.
- Sakai, Takahiro,Soeta, Takahiro,Inomata, Katsuhiko,Ukaji, Yutaka
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scheme or table
p. 231 - 235
(2012/04/23)
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- N-heterocyclic carbene-catalyzed hydrosilylation of styryl and propargylic alcohols with dihydrosilanes
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Reducing alkenes to tears: Addition of structurally diverse N-heterocyclic carbenes (NHCs) to silicon allows the reduction of propargylic and styryl alcohols through an organocatalyzed silylation/direct hydride transfer tandem reaction (see scheme). Catalytic turnover is enabled by the switch to and from hypervalent silicon. This provides a new synthetic application of NHC-main group element complexes. Copyright
- Zhao, Qiwu,Curran, Dennis P.,Malacria, Max,Fensterbank, Louis,Goddard, Jean-Philippe,Lacote, Emmanuel
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supporting information; experimental part
p. 9911 - 9914
(2011/10/05)
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- The reaction of acetal-type protective groups in combination with TMSOTf and 2,2′-bipyridyl; Mild and chemoselective deprotection and direct conversion to other protective groups
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A mild and chemoselective deprotection method of various acetal-type protective groups, such as MOM, MEM, BOM, and SEM ethers, has been developed. The combination of TMSOTf and 2,2′-bipyridyl was very effective for the deprotection, and the reaction proceeded via the formation of pyridinium intermediates, which were hydrolyzed to the corresponding alcohols in good to high yields. The features of this method are mild (almost neutral) reaction conditions and the tolerability of acid-sensitive functional groups. This method is also applicable for the direct conversion of MOM ether to BOM or SEM ether using the appropriate alcohols instead of H2O.
- Fujioka, Hiromichi,Minamitsuji, Yutaka,Kubo, Ozora,Senami, Kento,Maegawa, Tomohiro
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experimental part
p. 2949 - 2960
(2011/05/12)
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- A tetranuclear-zinc-cluster-catalyzed practical and versatile deprotection of acetates and benzoates
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A new catalytic deacylation of acetates and benzoates through transesterification with methanol was developed (see scheme). Reactions with various acidand nucleophile-sensitive functional groups proceeded efficiently in the presence of a catalytic amount of the tetranuclear zinc cluster. The present catalysis is applicable to less-reactive tertiary acetates, the deacylation of which is difficult to achieve by transesterification with other catalysts.
- Iwasaki, Takanori,Agura, Kazushi,Maegawa, Yusuke,Hayashi, Yukiko,Ohshima, Takashi,Mashima, Kazushi
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supporting information; experimental part
p. 11567 - 11571
(2010/11/24)
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- Remarkable effect of 2,2′-bipyridyl: Mild and highly chemoselective deprotection of methoxymethyl (MOM) ethers in combination with TMSOTf (TESOTf)-2,2′-bipyridyl
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The remarkable effect of 2,2′-bipyridyl led to the successful development of the mild and highly chemoselective deprotection method of methoxymethyl (MOM) ethers using the combination of TMSOTf (or TESOTf) and 2,2′-bipyridyl; this method can be applied to the direct conversion of the MOM group to other ethereal protective groups (e.g. benzyloxymethyl) with the corresponding alcohols. The Royal Society of Chemistry 2009.
- Fujioka, Hiromichi,Kubo, Ozora,Senami, Kento,Minamitsuji, Yutaka,Maegawa, Tomohiro
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supporting information; experimental part
p. 4429 - 4431
(2009/12/29)
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- Direct addition of supercritical alcohols, acetone or acetonitrile to the alkenes without catalysts
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The reactions of the alkenes with supercritical organic compounds under non-catalytic conditions were investigated. The H and CR2OH, CH2C{double bond, long}OCH3 or CH2C{triple bond, long}N of supercritical alcohols (CHR2OH), acetone (CH3C{double bond, long}OCH3) or acetonitrile (CH3C{triple bond, long}N) added to the C{double bond, long}C bonds of alkenes form C-C bonds between the α-carbons of the supercritical organic compounds and the sp2 carbons of the alkenes.
- Kamitanaka, Takashi,Hikida, Tatsuyoshi,Hayashi, Satoshi,Kishida, Nobuhiro,Matsuda, Tomoko,Harada, Tadao
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p. 8460 - 8463
(2008/03/13)
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- A new synthetic method for methyl ketones from carboxylic acids using metallic strontium and methyl iodide
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Carboxylic acids reacted with metallic strontium and methyl iodide to give methyl ketones preferentially in moderate to good yields. Copyright
- Miyoshi, Norikazu,Matsuo, Tsuyoshi,Asaoka, Masashi,Matsui, Aki,Wada, Makoto
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- The chemistry of alkylstrontium halide analogues, Part 2: Barbier-type dialkylation of esters with alkyl halides
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The chemistry of an alkylstrontium halide analogue was examined. In the presence of metallic strontium, the Barbier-type alkylation of esters with alkyl iodides proceeded smoothly at room temperature, under argon, to afford the corresponding dialkylated alcohols in good yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Miyoshi, Norikazu,Matsuo, Tsuyoshi,Wada, Makoto
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p. 4253 - 4255
(2007/10/03)
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- Picolinyl group as an efficient alcohol protecting group: Cleavage with Zn(OAc)2·2H2O under a neutral condition
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As an efficient alcohol protecting group, picolinates (Pic), prepared from the corresponding alcohols using commercial picolinoyl chloride, are readily cleaved by Zn(OAc)2 or Cu(OAc)2, even in the presence of other common alcohol protecting groups. Moreover, the picolinyl group at C-2 position in carbohydrates can be selectively cleaved to give methyl 4,6-O-benzylidene-3-O-picolinyl-α-d-glucopyranoside and 3-O-picolinyl methyl-4,6-O-benzylidene-α-d-galactopyranoside in good yields.
- Ju, Yuel Baek,Shin, Yong-Joo,Heung, Bae Jeon,Kwan, Soo Kim
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p. 5143 - 5147
(2007/10/03)
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- The Barbier-Type Alkylation of Aldehydes with Alkyl Halides in the Presence of Metallic Strontium
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In the presence of metallic strontium, the Barbier-type alkylation of aldehydes with alkyl iodides proceeded smoothly at - 15 °C under an argon atmosphere to afford the corresponding alkylated alcohols in moderate to good yields. The unusual addition reaction of ethyl benzoate with tert-butyl iodide took place to give the p-tert-butylated alkylated product (the 1,6-adduct of the benzoate) in 55% yield. Using strontium isopropoxide, the Meerwein-Ponndorf-Verley-type reduction of the aldehyde proceeded smoothly under reflux conditions in 2-propanol.
- Miyoshi, Norikazu,Kamiura, Koji,Oka, Hiromi,Kita, Akiko,Kuwata, Rika,Ikehara, Daitetsu,Wada, Makoto
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p. 341 - 345
(2007/10/03)
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- First Carbamates Conversion to Amides by Simple Alkyl Group Transfer from Trialkylalanes
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(Equation presented) N-Monosubstituted carbamates are cleanly converted to amides under treatment with trialkylaluminum. This reaction involves an aluminum-assisted internal delivery of alkyl groups. It can be applied to new and mild protecting group strategies for alcohols.
- El Kaim, Laurent,Grimaud, Laurence,Lee, Anabelle,Perroux, Yannick,Tirla, Cornelia
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p. 381 - 383
(2007/10/03)
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- DTBB-Catalysed dilithiation of styrene and its methyl-derivatives: Introduction of two electrophilic reagents
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The reaction of styrene and some methyl-substituted styrenes 1 with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) in the presence of several electrophiles [Me3SiCl, Me2CO, Et2CO, (CH2)5CO, Pr2CO], in THF, at temperatures ranging from -78 to 0°C, gave, after hydrolysis, products 2 resulting from addition of lithium to the olefinic double bond and successive trapping with the electrophilic reagent. When a carbonyl compound was used as electrophile, mixtures of the monoaddition-reduction compounds 3 and 4 were obtained as by-products, which could be easily separated from the diaddition products 2.
- Yus, Miguel,Martínez, Pedro,Guijarro, David
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p. 10119 - 10124
(2007/10/03)
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- Selective liquid-phase semihydrogenation of functionalized acetylenes and propargylic alcohols with silica-supported bimetallic palladium-copper catalysts
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Silica-supported, bimetallic palladium-copper catalysts were prepared in solution under mild conditions by reacting lithium di(4-tolyl)cuprate with palladium acetate in the presence of silica particles. Small bimetallic palladium-copper particles were deposited on the silica surface as confirmed with TEM-EDAX and EXAFS. The new material has been applied as catalyst in the liquid-phase semihydrogenation of mono- and disubstituted alkynes and showed high selectivity toward the cis-alkenes. The influence of addition of quinoline or potassium hydroxide to the semihydrogenation reaction mixture and the effects of exposure of the catalyst to air before use have been investigated. Silica-supported, bimetallic palladium-copper catalysts were prepared in solution under mild conditions by reacting lithium di(4-tolyl)cuprate with palladium acetate in the presence of silica particles. Small bimetallic palladium-copper particles were deposited on the silica surface as confirmed with TEM-EDAX and EXAFS. The new material has been applied as catalyst in the liquid-phase semihydrogenation of mono- and disubstituted alkynes and showed high selectivity toward the cis-alkenes. The influence of addition of quinoline or potassium hydroxide to the semihydrogenation reaction mixture and the effects of exposure of the catalyst to air before use have been investigated.
- Spee,Boersma,Meijer,Slagt,Van Koten,Geus
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p. 1647 - 1656
(2007/10/03)
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- Conjugative interaction in styrenes
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Conjugative interactions of the carbon-carbon double bond are fundamental in organic chemistry. In this work, equilibria are established among conjugated and unconjugated isomers of two β-substituted styrenes, 1-phenylbut-1-ene and 1-phenyl-3-methylbut-1-ene, and one α,β-disubstituted styrene, 2-phenyl-5-methylhex-2-ene, over a range of temperatures (the van't Hoff method) in hexamethylphosphoric triamide and potassium tert-butoxide. From the trans styrenes of the first two sets, an enthalpy of conjugative interaction of phenyl vis-a-vis alkyl (ΔΔH(ConjInter/Alk)) = -2.5 ± 0.2 kcal/mol [-5.1 kcal/mol defined as phenyl vis-a-vis hydrogen (ΔΔH(ConjInter/H))] is observed, while the cis styrenes reveal an attenuated ΔΔH(ConjInter/Alk) of -1.1 kcal/mol (ΔΔH(ConjInter/H)) = -2.7 kcal/ mol). The α-methyl group in the third set also leads to a reduced conjugative interaction. Entropy plays an important role in determining positions of equilibrium. Free energies of conjugation are reported for several sterically hindered o-methyl-substituted styrenes.
- Von Doering,Benkhoff, Johannes,Carleton, Peter Smart,Pagnotta, Marco
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p. 10947 - 10955
(2007/10/03)
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- The reaction of alkyl peroxy radicals
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Secondary alkyl peroxy radicals generated from 4-phenyl-2-butyl-, 2-nonyl- and 3α-cholestanyl hydroperoxides at 45°C undergo Russell termination reactions in preference to non-terminating decomposition reactions. Non-terminating decomposition of 2-nonyl peroxy radicals afforded 2,5-nonanedione and 2,5-nonanediol due to intramolecular hydrogen abstraction reactions of alkoxy radicals. The radicals derived from 2-methyl-4-phenyl-2-butyl-, 2-methyl-5-phenyl-2-pentyl- and 2-methyl-6-phenyl-2-hexyl hydroperoxides afforded benzylic functionalized products due to intermolecular reactions. 2-Hexylperoxy radicals generated in excess alcohols ineffectively abstracted the α-hydrogens of alcohols. These results demonstrate the low reactivity of alkyl peroxy radicals.
- Goosen, Andre,Kindermans, Sybrandus
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- A Novel C-C Single-Bond Formation Accompanying C-O Bond Cleavage by Use of a Ketone, an Alkylating Reagent, and a Low-Valent Vanadium Complex in the Presence of a Catalytic Amount of Molecular Oxygen
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A C-C single-bond-forming reaction from ketones with accompanying C-O bond cleavage mediated by a RMgBr or RLi-vanadium(II)-O2 system has been accomplished. Different from conventional reductive coupling reactions of ketones such as the McMurry coupling, the present method forms a C-C single (instead of a double) bond and yields a product that contains components derived from the ketone and the alkylating reagent in a one-pot reaction. Collaboration of both a low-valent vanadium(II) species and a higher-valent vanadium species produced from vanadium(II) and a catalytic amount of O2 effects the abstraction of the oxygen atom from a C-O bond.
- Kataoka, Yasutaka,Akiyama, Hiroaki,Makihira, Isamu,Tani, Kazuhide
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p. 8109 - 8113
(2007/10/03)
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- Samarium(II) triflate as a new reagent for the grignard-type carbonyl addition reaction
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On treatment of a THF solution of Sm(OTf)3 with 1 equiv of an organolithium or organomagnesium reagent at ambient temperature, the purple or deep green solution of the divalent samarium triflate [Sm(OTf)2] was readily obtained. For this preparation, s-BuLi was the most effective as was evidenced by the reduction of 2-phenylethyl iodide in the presence of HMPA. The Sm(OTf)2 reagent mediated the Grignard-type reaction effectively in THF/HMPA; alkylation and allylation of ketones or aldehydes with alkyl, allyl, or benzyl halides proceeded via organosamarium intermediates. Diastereoselectivity of the samarium-Grignard reaction was examined using 2-methylcyclohexanone, 4-tert-butylcyclohexanone, and 2-phenylpropanal and was found to be higher in each case than that with SmI2. With 2-methylcyclohexanone, for example, Sm(OTf)2 gave the greatest ratio of axial alcohol:equatorial alcohol = 99:1, and SmI2 gave a ratio of 91:9. Halides containing an ester or a silyl group were reactive in the Reformatsky- or Peterson-type reaction, respectively, using the Sm(OTf)2 reagent.
- Fukuzawa, Shin-Ichi,Mutoh, Keisuke,Tsuchimoto, Teruhisa,Hiyama, Tamejiro
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p. 5400 - 5405
(2007/10/03)
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- The Phenyldimethylsilyl Group as a Masked Hydroxy Group
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A phenyldimethylsilyl group attached to carbon can be converted into hydroxy group 1->5, with retention of configuration at the migrating carbon, by any of three main methods.The first involves protodesilylation, to remove the phenyl ring from the silicon atom, followed by oxidation of the resulting functionalized silicon atom using peracid or hydrogen peroxide.The second uses mercuric acetate for the same purpose, and can be combined in one pot with the oxidative step using peracetic acid.This method has a variant in which the mercuric ion is combined with palladium(II) acetate, both in less than stoichiometric amounts.The third uses bromine, which can also be used in one pot in conjuction with peracetic acid.In this method, but not in the method based on mercuric acetate, the peracetic acid may be buffered with sodium acetate.The method using bromine as the electrophile for removing the benzene ring has a more agreeable variant in which it is administered in the form of potassium bromide, which is oxidised to bromine by the peracetic acid.The scope and limitations of each of these methods are reported with a range of examples possessing between them many of the common functional groups.Simple benzene rings, alcohols, ethers, esters, amides and nitriles are compatible with all three methods, and ketones do not undergo Baeyer-Villiger reaction under any of the conditions.Amines, however, are oxidised to amine oxides.Ketones may be brominated in the third of the three main species.The absence of acid in the third method makes it especially valuable when the phenyldimethylsilyl group has a neighbouring nucleofugal group such as hydroxy or acetoxy.Carbon-carbon double bonds are incompatible with the methods, except for terminal monosubstituted double bonds, which can survive the conditions used in the first of the three methods.
- Fleming, Ian,Henning, Rolf,Parker, David C.,Plaut, Howard E.,Sanderson, Philip E. J.
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p. 317 - 338
(2007/10/02)
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- Preparation of Samarium(II) Triflate and It Mediated Grignard-type Reaction. In Situ Formation and Reaction of New Organosamarium Reagents
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Samarium(II) triflate was readily prepared by reaction of samarium(III) triflate with sec-butyllithium at room temperature in THF.Its reducing ability was examined by pinacol coupling of carbonyl compounds.Sm(OTf)2 mediated Grignard-type reaction in THF-HMPA effectively; alkylation and allylation of ketones or aldehydes by simple alkyl, allyl, and benzyl halides proceeded via organosamarium intermediates.
- Fukuzawa, Shin-ichi,Tsuchimoto, Teruhisa,Kanai, Takeshi
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p. 1981 - 1984
(2007/10/02)
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