- Titanocene(II)-promoted stereoselective alkenylation utilizing (Z)-alkenyl sulfones
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(Chemical Equation Presented) The stereoselective alkenylation of unsaturated compounds by means of a (Z)-alkenyl sulfone-titanocene-(II) system is described. Treatment of alkynes and (Z)-alkenyl methyl sulfones with the titanocene(II) reagent Cp2Ti[P(OEt)3]2 produced conjugated dienes. This alkenylation system is also applicable to polar C=O bonds; the simple mixing of carbonyl compounds, (Z)-alkenyl methyl sulfones, and the titanocene-(II) reagent formed allylic alcohols. The advantages of alkenylation are that it requires no prepreparation of the alkenylmetal reagent and that it proceeds with complete stereoselectivity.
- Ogata, Akitoshi,Nemoto, Masami,Kobayashi, Kenji,Tsubouchi, Akira,Takeda, Takeshi
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- Facile Direct Coupling Reactions of MOM-protected Benzylic Alcohols Using Aluminum Chloride
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MOM group is one of the most commonly used protecting groups for alcohols. This study describes novel direct functionalization of the MOM-protected benzylic alcohols. Preparation of allylic compounds from benzyl MOM ethers was successfully achieved by utilization of allyltrimethylsilane and AlCl3. In addition, direct azidation of benzyl MOM ethers using TMSN3 was successful carried out under AlCl3-mediated reaction conditions. These results demonstrate that this novel synthetic procedure is a promising approach to direct functionalization of MOM-protected alcohols including allylation and azidation.
- Bui, Tien Tan,Kim, Hee-Kwon
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supporting information
p. 1195 - 1198
(2021/08/03)
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- Direct AlCl3-catalyzed transformation of benzyl THP ethers and allyl benzyl ethers
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THP and allyl groups are frequently used for the protection of alcohols. In this study, novel direct transformations of benzyl THP ethers and allyl benzyl ethers, protected forms of alcohols, are reported. TMSN3 and AlCl3 were employ
- Bui, Tien Tan,Kim, Hee-Kwon
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p. 388 - 397
(2020/10/15)
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- Dual Nickel- And Photoredox-Catalyzed Reductive Cross-Coupling of Aryl Halides with Dichloromethane via a Radical Process
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The first catalytic strategy to harness a new chloromethane radical from dichloromethane under dual Ni/photoredox catalytic conditions has been developed. Compared with traditional two-electron reductive process associated with metallic reductants, this method via a single-electron approach can proceed under exceptionally mild conditions (visible light, ambient temperature, no strong base) and exhibits complementary reactivity patterns. It affords a broad scope of many functional groups, including alkenyl, which suffers cyclopropanation in previous routes. The diarylmethane-d2 compounds can be readily available with this transformation.
- Xu, Tao,Xu, Wenhao,Zheng, Purui
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supporting information
(2020/11/13)
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- Arylboronic Acid Catalyzed C-Alkylation and Allylation Reactions Using Benzylic Alcohols
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The arylboronic acid catalyzed dehydrative C-alkylation of 1,3-diketones and 1,3-ketoesters using secondary benzylic alcohols as the electrophile is reported, forming new C-C bonds (19 examples, up to 98% yield) with the release of water as the only byproduct. The process is also applicable to the allylation of benzylic alcohols using allyltrimethylsilane as the nucleophile (12 examples, up to 96% yield).
- Estopi?á-Durán, Susana,McLean, Euan B.,Donnelly, Liam J.,Hockin, Bryony M.,Taylor, James E.
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supporting information
p. 7547 - 7551
(2020/10/09)
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- Controllable Isomerization of Alkenes by Dual Visible-Light-Cobalt Catalysis
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We report herein that thermodynamic and kinetic isomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction further. Transformation of exocyclic alkenes into the corresponding endocyclic products could be efficiently realized by using 4CzIPN and Co(acac)2 in the absence of any additional ligands. Spectroscopic and spectroelectrochemical investigations indicate CoI being involved in the generation of a Co hydride, which subsequently adds to alkenes initiating the isomerization.
- Meng, Qing-Yuan,Schirmer, Tobias E.,Katou, Kousuke,K?nig, Burkhard
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supporting information
p. 5723 - 5728
(2019/04/03)
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- Metal-free synthesis of gem -silylboronate esters and their Pd(0)-catalyzed cross-coupling with aryliodides
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A transition-metal-free method for the synthesis of gem-silylboronate esters with arylboronic acids and trimethylsilyldiazomethane (TMSCHN2) has been developed. This transformation is a straightforward homologation of arylboronic acids and features wide substrate scope and good functional-group tolerance. The gem-silylboronate esters undergo efficient Suzuki-Miyaura cross-coupling with aryliodides and the silyl group of the product can be further functionalized. Tertiary carbon centers with different substituents can be constructed successfully by selective and sequential functionalization.
- Wu, Chaoqiang,Bao, Zhicheng,Xu, Xing,Wang, Jianbo
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p. 5714 - 5724
(2019/06/18)
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- Rhenium complex-catalyzed carbon-carbon formation of alcohols and organosilicon compounds
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The coupling reactions of allylic and benzylic alcohols and allyltrimethylsilane are efficiently catalyzed by a rhenium complex to give the corresponding 1,5-dienes and alkenes in moderate to good yields. Similarly, alcohols were coupled with ketene silyl acetals to form the corresponding esters.
- Umeda, Rui,Jikyo, Toshifumi,Toda, Kazuki,Osaka, Issey,Nishiyama, Yutaka
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supporting information
p. 1121 - 1124
(2018/02/21)
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- Testing the veracity of claims of Lewis acid catalysis
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Are reactions employing Lewis acids really catalysed by those Lewis acids, or by “hidden Br?nsted acids”, i.e. Br?nsted acids generated in situ by hydrolysis? Testing of a series of reactions using Sc(III), Fe(III), In(III) and Y(III) by addition of 2,6-di-t-butyl-4-methylpyridine reveal that all are likely to follow the latter pathway. A reaction claimed to be catalysed by CBr4 through halogen bonding is also likely to be Br?nsted acid catalysed.
- ?oli?, Ivan,Lin, Hong Xuan,Bates, Roderick W.
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supporting information
p. 4434 - 4436
(2018/11/23)
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- Silylated cyclopentadienes as competent silicon Lewis acid catalysts
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The synthesis and characterization of silicon Lewis acid complexes that incorporate highly electron-deficient cyclopentadienes is reported. Several pentacarboxycyclopentadienyl and monocarboxytetracyanocyclopentadienyl complexes were prepared. A comparison of their reactivities for catalysis of the allylation of an electron-deficient benzaldehyde was established. The use of a monocarboxytetracyano silylium donor was shown to be effective for the allylation or arylation of a variety of electrophiles via an anion abstraction pathway.
- Radtke, M. Alex,Lambert, Tristan H.
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p. 6406 - 6410
(2018/08/12)
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- Carbon—carbon and carbon—nitrogen bond formation reactions catalyzed by the magnesium and calcium acenaphthene-1,2-diimine complexes
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A mixture of allylbromide and diphenylacetonitrile is reduced to afford 2,2-diphenylpentene-4-nitrile as a major product in the presence of catalytic amounts of the magnesium complex (dpp-bian)Mg(thf)3 (dpp-bian is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene dianion). The overall conversion of nitrile is 71% within 3 h at 85 °С. 4,4-Diphenylbutene-1 and diphenylmethane are by-products in this process. Complexes (dpp-bian)Mg(thf)3 and (dpp-bian)Ca(thf)4 (in an amount of 0.5—5 mol.%) catalyze the intramolecular hydroamination of some aminopentenes and aminohexenes with the conversion from 67 to 99%.
- Yakub,Moskalev,Bazyakina,Fedushkin
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p. 473 - 478
(2018/07/06)
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- Carbenium ion formation by fragmentation of electrochemically generated oxonium ions
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Fragmentation of electrochemically generated oxonium ions can be exploited to form carbenium ions at a low oxidation potential in the presence of a nucleophile. The application of this concept is demonstrated for the allylation of carbenium ions generated by the anodic oxidation of stannylmethylethers.
- Lielpetere, Anna,Jirgensons, Aigars
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supporting information
p. 5094 - 5096
(2018/07/29)
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- Promoter free allylation of trichloroacetimidates with allyltributylstannanes under thermal conditions to access the common 1,1′-diarylbutyl pharmacophore
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1,1′-Diarylbutyl groups are a common pharmacophore found in many biologically active small molecules. To access these systems under mild conditions, the reaction of diarylmethyl trichloroacetimidates with allyltributylstannanes was explored. Simply heating allyltributylstannane with the trichloroacetimidate resulted in substitution of the imidate with an allyl group. Unlike other methods used to access these systems, no strong base, transition metal catalyst, Br?nsted acid or Lewis acid promoter was required to affect the transformation. Conversions are best with electron rich benzylic trichloroacetimidate systems, where excellent yields are achieved just by refluxing the reactants together in nitromethane.
- Mahajani, Nivedita S.,Chisholm, John D.
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supporting information
p. 4008 - 4012
(2018/06/08)
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- Scandium as a pre-catalyst for the deoxygenative allylation of benzylic alcohols
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Scandium triflate is an effective pre-catalyst for the deoxygenative allylation of benzylic alcohols with a narrow substrate window. The reaction is shown to proceed through a "hidden Br?nsted acid" mechanism. The reaction is efficient provided that the aryl group is neither too electron rich nor too electron poor. It is shown that this allows useful selectivity. The reaction also works for benzyhydryl alcohols with broader scope. The reaction may also be catalysed by Nafion.
- ?oli?, Ivan,Seankongsuk, Pattarakiat,Loh, Joanna Kejun,Vilaivan, Tirayut,Bates, Roderick W.
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p. 119 - 123
(2017/12/27)
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- Direct allylation of benzyl alcohols, diarylmethanols, and triarylmethanols mediated by XtalFluor-E
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We report the direct allylation of benzyl alcohols, diarylmethanols and triarylmethanols mediated by XtalFluor-E using allyltrimethylsilane. The resulting allylated products are obtained in moderate to high yield.
- Lebleu, Thomas,Paquin, Jean-Fran?ois
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supporting information
p. 442 - 444
(2017/01/10)
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- Palladium-Catalyzed Electrochemical Allylic Alkylation between Alkyl and Allylic Halides in Aqueous Solution
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A new route for the direct cross-coupling of alkyl and allylic halides using electrochemical technique has been developed in aqueous media under air. Catalyzed by Pd(OAc)2, the Zn-mediated allylic alkylations proceed smoothly between a full range of alkyl halides (primary, secondary, and tertiary) and substituted allylic halides. Protection-deprotection of acidic hydrogen in the substrates is avoided.
- Lai, Yin-Long,Huang, Jing-Mei
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supporting information
p. 2022 - 2025
(2017/04/28)
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- Nickel-catalyzed allylic alkylation with diarylmethane pronucleophiles: Reaction development and mechanistic insights
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Palladium-catalyzed allylic substitution reactions are among the most efficient methods to construct C-C bonds between sp3-hybridized carbon atoms. In contrast, much less work has been done with nickel catalysts, perhaps because of the different mechanisms of the allylic substitution reactions. Palladium catalysts generally undergo substitution by a "soft"-nucleophile pathway, wherein the nucleophile attacks the allyl group externally. Nickel catalysts are usually paired with "hard" nucleophiles, which attack the metal before C-C bond formation. Introduced herein is a rare nickel-based catalyst which promotes substitution with diarylmethane pronucleophiles by the soft-nucleophile pathway. Preliminary studies on the asymmetric allylic alkylation are promising. Just a softy: Contrary to what would be predicted, organosodium nucleophiles derived from diarylmethane pronucleophiles are shown to behave as soft nucleophiles in nickel-catalyzed allylic substitution reactions. This general reaction is demonstrated to proceed through a double inversion pathway. A promising asymmetric version is presented.
- Sha, Sheng-Chun,Jiang, Hui,Mao, Jianyou,Bellomo, Ana,Jeong, Soo A.,Walsh, Patrick J.
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supporting information
p. 1070 - 1074
(2016/01/20)
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- A general Br?nsted acid-catalyzed allylation of benzhydryl alcohols
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Efficient Br?nsted acid-catalyzed allylation of benzhydryl alcohols has been developed. The reaction occurs within 5?min in the presence of sub-stoichiometric amounts of HBF4·OEt2to afford the desired products in good to excellent yields. A variety of functional groups were tolerated under the developed conditions including amides, aldehydes, hydroxyl and carboxylic acid.
- Orizu, Ifedi,Bolshan, Yuri
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supporting information
p. 5798 - 5800
(2016/12/03)
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- Metal catalyst-free substitution of allylic and propargylic phosphates with diarylmethyl anions
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Substitution of secondary allylic phosphates with the anions derived from Ar2CH2 with BuLi or LDA proceeded regioselectively and stereoselectively without a metal catalyst, affording inversion products in good yield. Similarly, propargylic phosphates gave propargylic products selectively.
- Kawashima, Hidehisa,Ogawa, Narihito,Saeki, Ryohei,Kobayashi, Yuichi
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supporting information
p. 4918 - 4921
(2016/04/10)
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- Direct Dehydroxylative Coupling Reaction of Alcohols with Organosilanes through Si-X Bond Activation by Halogen Bonding
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The combined use of a halogen bond (XB) donor with trimethylsilyl halide was found to be an efficient cocatalytic system for the direct dehydroxylative coupling reaction of alcohol with various nucleophiles, such as allyltrimethylsilane and trimethylcyanide, to give the corresponding adduct in moderate to excellent yields. Detailed control experiments and mechanistic studies revealed that the XB interaction was crucial for the reaction. The application of this coupling reaction is also described.
- Saito, Masato,Tsuji, Nobuya,Kobayashi, Yusuke,Takemoto, Yoshiji
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supporting information
p. 3000 - 3003
(2015/06/30)
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- Copper-Catalyzed Cross-Coupling Reaction of Allyl Boron Ester with 1°/2°/3°-Halogenated Alkanes
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The cross-coupling reaction of allyl boron ester with 1°/2°/3°-halogenated alkanes in the presence of copper has been developed for the first time, which provides a mild and efficient method for the construction of saturated C(sp3)-C(sp3) bonds. This protocol shows excellent compatibility with the nonactivated primary, secondary, and even tertiary halogenated alkanes under mild conditions.
- Wang, Guang-Zu,Jiang, Jian,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Jun,Fu, Yao,Xu, Hua-Jian
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supporting information
p. 3682 - 3685
(2015/08/18)
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- Flexible and biomimetic analogs of triple uptake inhibitor 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol: Synthesis, biological characterization, and development of a pharmacophore model
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In this study we have generated a pharmacophore model of triple uptake inhibitor compounds based on novel asymmetric pyran derivatives and the newly developed asymmetric furan derivatives. The model revealed features important for inhibitors to exhibit a
- Sharma, Horrick,Santra, Soumava,Debnath, Joy,Antonio, Tamara,Reith, Maarten,Dutta, Aloke
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p. 311 - 324
(2014/01/17)
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- Chemoselective and direct functionalization of methyl benzyl ethers and unsymmetrical dibenzyl ethers by using iron trichloride
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Methyl and benzyl ethers are widely utilized as protected alcohols due to their chemical stability, such as the low reactivity of the methoxy and benzyloxy groups as leaving groups under nucleophilic conditions. We have established the direct azidation of chemically stable methyl and benzyl ethers derived from secondary and tertiary benzyl alcohols. The present azidation chemoselectively proceeds at the secondary or tertiary benzylic positions of methyl benzyl ethers or unsymmetrical dibenzyl ethers and is also applicable to direct allylation, alkynylation, and cyanation reactions, as well as the azidation. The present methodologies provide not only a novel chemoselectivity but also the advantage of shortened synthetic steps, due to the direct process without the deprotection of the methyl and benzyl ethers. Ethers exchanged: Methyl and benzyl ethers are chemically stable and generally tolerant under nucleophilic substitution conditions. Iron-catalyzed direct functionalizations (e.g., azidation, allylation, alkynylation, and cyanation) of methyl and benzyl ethers derived from secondary and tertiary benzyl alcohols were established with excellent regioselectivities (see scheme; PG: protecting group; Bn: benzyl; Nu: nucleophile; TMS: trimethylsilyl). Copyright
- Sawama, Yoshinari,Goto, Ryota,Nagata, Saori,Shishido, Yuko,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 2631 - 2636
(2014/03/21)
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- Iron-catalyzed π-activated C-O ether bond cleavage with C-C and C-H bond formation
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A novel and efficient allylic alkylation reaction between π-activated ethers and allylsilane was realized under mild conditions through iron(III)-catalyzed C sp 3-O ether bond cleavage. The present protocol provides an attractive approach for the construction of sp3-sp3 C-C bonds and can be potentially applied for the selective reduction of benzyl and allyl ethers to their corresponding hydrocarbon compounds by using triethylsilane as a hydride-transfer reagent. A mild, economical, and environmentally friendly method for the construction of C sp 3-C sp 3 bonds through iron-catalyzed π-activated C-O ether bond cleavage is developed. In addition, this catalytic system can be used for the selective reduction of benzylic and allylic C-O ether bonds to C-H bonds. Copyright
- Fan, Xiaohui,Cui, Xiao-Meng,Guan, Yong-Hong,Fu, Lin-An,Lv, Hao,Guo, Kun,Zhu, Hong-Bo
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supporting information
p. 498 - 501
(2014/02/14)
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- Iron-Catalyzed π-Activated C-O Ether Bond Cleavage with C-C and C-H Bond Formation
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A novel and efficient allylic alkylation reaction between π-activated ethers and allylsilane was realized under mild conditions through iron(III)-catalyzed C sp 3-O ether bond cleavage. The present protocol provides an attractive approach for the construction of sp3-sp3 C-C bonds and can be potentially applied for the selective reduction of benzyl and allyl ethers to their corresponding hydrocarbon compounds by using triethylsilane as a hydride-transfer reagent.
- Fan, Xiaohui,Cui, Xiao-Meng,Guan, Yong-Hong,Fu, Lin-An,Lv, Hao,Guo, Kun,Zhu, Hong-Bo
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supporting information
p. 498 - 501
(2015/10/05)
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- Raising the p K a Limit of soft nucleophiles in palladium-catalyzed allylic substitutions: Application of diarylmethane pronucleophiles
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The Tsuji-Trost allylic substitution reaction provides a useful and efficient approach to construct C-C bonds between sp3-hybridized carbons. The widely accepted paradigm for classifying the mode of attack of nucleophiles on palladium π-allyl intermediates in the Tsuji-Trost reaction is based on the pKa of the pronucleophile: (1) stabilized or soft carbon nucleophiles and heteroatom nucleophiles (e.g., pronucleophiles with pKa's a's > 25). One of the keys to the continuing development of allylic substitution processes remains broadening the scope of soft nucleophiles. Herein we report a general method for the room temperature Pd-catalyzed allylic substitution with diarylmethane derivatives (pKa's up to 32). The synthetic significance of the method is that it provides a rapid access to products containing allylated diarylmethyl motifs. The method is general for a wide range of nucleophiles derived from diarylmethanes and heterocyclic derivatives. A procedure for the Pd-catalyzed allylic substitutions to afford diallylation products with quaternary centers is also described. With triarylmethanes and alkylated diarylmethanes the corresponding allylated products are isolated. We anticipate that the described method will be a valuable complement to the existing arsenal of nucleophiles in Pd-catalyzed allylic substitutions. Mechanistic studies show that the nucleophile derived from diphenylmethane undergoes external attack on π-allyl palladium species under our reaction conditions. This unexpected observation indicates that diarylmethane derivatives behave as soft or stabilized nucleophiles. The results of this study indicate that the cutoff between soft and hard nucleophiles should be raised from a pronucleophile pK a of 25 to at least 32.
- Sha, Sheng-Chun,Zhang, Jiadi,Carroll, Patrick J.,Walsh, Patrick J.
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supporting information
p. 17602 - 17609
(2014/01/06)
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- High-yielding and rapid carbon-carbon bond formation from alcohols: Allylation by means of TiCl4
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TiCl4 efficiently promotes high yield (80-99%) replacement of OH in tertiary, benzylic, and allylic alcohols, and even nonactivated secondary alcohols, by an allyl group. The reaction usually proceeds within minutes at room temperature. Georg Thieme Verlag Stuttgart. New York.
- Hassner, Alfred,Bandi, Chennakesava Reddy
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p. 1275 - 1279
(2013/07/11)
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- Facile coupling of propargylic, allylic and benzylic alcohols with allylsilane and alkynylsilane, and their deoxygenation with Et3SiH, catalyzed by Bi(OTf)3 in [BMIM][BF4] ionic liquid (IL), with recycling and reuse of the IL
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Allyltrimethylsilane (allyl-TMS) reacts with propargylic alcohols 1a-1d in the presence of 10% Bi(OTf)3 in [BMIM][BF4] solvent to furnish the corresponding 1,5-enynes in respectable isolated yields (87-93%) at room temperature. The utility of Bi(OTf)3 as a superior catalyst was demonstrated in a survey study on coupling of allyl-TMS with 1a employing several metallic triflates (Bi, Ln, Al, Yb) as well as, B(C6F 5)3, Zn(NTf2)2 and Bi(NO 3)3·5H2O. Coupling of cyclopropyl substituted propargylic alcohol 1e with allyl-TMS gave the skeletally intact 1,5-enyne and a ring opened derivative as a mixture. Coupling of propargylic/allylic alcohol 1f with allyl-TMS resulted in allylation at both benzylic (2 isomers) and propargylic positions, as major and minor products respectively. The scope of this methodology for allylation of a series of allylic and benzylic alcohols was explored. Chemoselective reduction of a host of propargylic, propagylic/allylic, bis-allylic, allylic, and benzylic alcohols with Et3SiH was achieved in high yields with short reaction times. The same approach was successfully applied to couple representative propargylic and allylic alcohols with 1-phenyl-2-trimethylsilylacetylene. The recovery and reuse of the ionic liquid (IL) was gauged in a case study with minimal decrease in isolated yields after six cycles.
- Narayana Kumar,Laali, Kenneth K.
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experimental part
p. 7347 - 7355
(2012/09/25)
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- Carbon-based leaving group in substitution reactions: Functionalization of sp3-hybridized quaternary and tertiary benzylic carbon centers
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Lewis acid promoted substitution reactions employing Meldrum's acid and 5-methyl Meldrum's acid as carbon-based leaving groups are described which transform unstrained quaternary and tertiary benzylic Csp 3-Csp3 bonds into Csp3-X bonds (X = C, H, N). Importantly, this reaction has a broad scope in terms of both suitable substrates and nucleophiles with good to excellent yields obtained (typically >90%).
- Mahoney, Stuart J.,Lou, Tiantong,Bondarenko, Ganna,Fillion, Eric
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p. 3474 - 3477
(2012/09/05)
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- HClO4-supported on silica gel: A mild and efficient catalyst for Hosomi-Sakurai reaction
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Perchloric acid supported on silica gel was found to be an efficient catalyst (2 mol %) for the Hosomi- Sakurai allylation of numerous aldehydes with allyltrimethylsilane in the presence of benzyl alcohol. This method was also effective for the allylation of secondary alcohols under mild experimental conditions.
- Murugan, Kaliyappan,Chen, Chinpiao
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experimental part
p. 5827 - 5830
(2011/12/03)
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- Palladium-catalyzed allylic substitution with (η6-Arene- CH2Z)Cr(CO)3-based nucleophiles
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Although the palladium-catalyzed Tsuji-Trost allylic substitution reaction has been intensively studied, there is a lack of general methods to employ simple benzylic nucleophiles. Such a method would facilitate access to "α-2-propenyl benzyl" motifs, which are common structural motifs in bioactive compounds and natural products. We report herein the palladium-catalyzed allylation reaction of toluene-derived pronucleophiles activated by tricarbonylchromium. A variety of cyclic and acyclic allylic electrophiles can be employed with in situ generated (η6-C 6H5CHLiR)Cr(CO)3 nucleophiles. Catalyst identification was performed by high throughput experimentation (HTE) and led to the Xantphos/palladium hit, which proved to be a general catalyst for this class of reactions. In addition to η6-toluene complexes, benzyl amine and ether derivatives (η6-C6H5CH 2Z)Cr(CO)3 (Z = NR2, OR) are also viable pronucleophiles, allowing C-C bond-formation α to heteroatoms with excellent yields. Finally, a tandem allylic substitution/demetalation procedure is described that affords the corresponding metal-free allylic substitution products. This method will be a valuable complement to the existing arsenal of nucleophiles with applications in allylic substitution reactions.
- Zhang, Jiadi,Stanciu, Corneliu,Wang, Beibei,Hussain, Mahmud M.,Da, Chao-Shan,Carroll, Patrick J.,Dreher, Spencer D.,Walsh, Patrick J.
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supporting information; experimental part
p. 20552 - 20560
(2012/02/13)
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- Fe(OTf)3-catalyzed reaction of benzylic acetates with organosilicon compounds
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Fe(OTf)3-catalyzed reaction of benzylic acetates with allyltrimethylsilane, azidotrimethylsilane, and cyanotrimethylsilane afforded the corresponding allylated, azido, and cyano products in high yields. 2-Trimethylsilyl-substituted benzofuran and indole worked well to furnish the benzyl-substituted benzofuran and indoles. Georg Thieme Verlag Stuttgart New York.
- Chan, Li Yan,Kim, Sundae,Chung, Wan Ting,Long, Chong,Kim, Sunggak
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experimental part
p. 415 - 419
(2011/04/22)
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- "Design" of boron-based compounds as pro-nucleophiles and co-catalysts for indium(I)-catalyzed allyl transfer to various Csp 3-type electrophiles
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We have recently uncovered a general indium(I)-catalyzed method for allylations and propargylation of acetals and ketals with a water- and air-stable allyl boronate. By using a more reactive allyl borane, we have successfully extended this methodology to the more challenging C-C coupling with ethers. Herein, we report an improved methodology for the indium(I)-catalyzed allylation of acetals and ethers, through combination of the allyl boronate with a commercially available "hard" Lewis acid, B-methoxy-9-BBN (BBN=borabicyclo[3.3.1]nonane), as an effective co-catalyst. Significantly, our work highlights for the first time the correlation between the Lewis acidity of "electrophilic" boron-based compounds and their " nucleophilic" reactivity in Csp3-Csp3 couplings, catalyzed by a "soft" low-oxidation main group metal. In addition, we also report several applications of these methodologies to the selective synthesis of various carbohydrate derivatives. Copyright
- Dao, Hai Thanh,Schneider, Uwe,Kobayashi, Shu
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experimental part
p. 2522 - 2529
(2012/07/13)
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- Indium(i)-catalyzed alkyl-allyl coupling between ethers and an allylborane
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An efficient method for alkyl-allyl cross-coupling between ethers and a 9-BBN-derived allylborane catalyzed by indium(i) triflate has been developed. The allylborane proved to be essential to obtain the desired products in high yields. The reaction displayed good substrate scope including high functional group tolerance. The Royal Society of Chemistry 2011.
- Dao, Hai Thanh,Schneider, Uwe,Kobayashi, Shu
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scheme or table
p. 692 - 694
(2011/03/22)
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- Rhodium-catalyzed allylation of benzyl acetates with allylsilanes
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Benzyl acetate reacted with allyltrimethylsilane to give an allylation product in the presence of a catalytic amount of the (cyclooctadiene)rhodium(I) chloride dimer {[Rh(cod)Cl]2}, sodium tetrakis[3,5- bis(trifluoromethyl)phenyl]borate (NaBARF), and triphenyl phosphite [P(OPh) 3] in refluxing 1,2-dichloroethane. Primary, secondary and tertiary benzyl acetates could be used for the reaction. Moreover, allylation of gem-benzyl acetate was possible with [Rh(cod)Cl]2, NaBARF, and P(OPh)3. Monoallylation and diallylation of gem-benzyl acetate could be controlled by altering the reaction conditions. Cationic rhodium species generated in situ act as a Lewis acid catalyst to give a benzyl carbocation by elimination of the acetoxy group from the benzylic carbon. Copyright
- Onodera, Gen,Yamamoto, Eriko,Tonegawa, Shota,Iezumi, Makoto,Takeuchi, Ryo
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scheme or table
p. 2013 - 2021
(2011/10/09)
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- Efficient and mild iron-catalyzed direct allylation of benzyl alcohols and benzyl halides with allyltrimethylsilane
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An efficient and mild iron-catalyzed direct allylation of benzyl alcohols and benzyl halides with allyltrimethylsilane has been developed. The present reaction would provide an excellent alternative to published methods because of its excellent yields, sustainable catalyst, and mild conditions. Copyright Taylor & Francis Group, LLC.
- Han, Jie,Cui, Zili,Wang, Jianguo,Liu, Zhongquan
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experimental part
p. 2042 - 2046
(2010/08/13)
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- Direct allylation of α-aryl alcohols with allyltrimethylsilane catalyzed by heterogeneous tin ion-exchanged montmorillonite
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The direct allylation of α-aryl alcohols with allyltrimethylsilane efficiently proceeded in the presence of tin ion-exchanged montmorillonite under mild conditions according to the proper addition order of reactants and a catalyst.
- Wang, Jiacheng,Masui, Yoichi,Onaka, Makoto
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experimental part
p. 3300 - 3303
(2010/07/06)
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- Direct coupling reaction between alcohols and allyltrimethylsilane catalyzed by phosphomolybdic acid
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Phosphomolybdic acid (PMA) is a simple and efficient catalyst for direct coupling reaction of alcohols with allyltrimethylsilane. Direct nucleophilic allylation of alcohol with allyltrimethylsilane proceeds in considerably good yield in the presence of catalytic amount of (0.5 mol %) PMA at room temperature. Copyright
- Kadam, Santosh T.,Lee, Hanbin,Kim, Sung Soo
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scheme or table
p. 67 - 70
(2010/11/04)
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- O-Benzenedisulfonimide as a reusable broonsted acid catalyst for hosomi-sakurai reactions
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Various acetals or alcohols react with allyl(trimethyl)silane or 1-phenyl-2-(trimethylsilyl)acetylene in the presence of a catalytic amount of the Bronsted acid o-benzenedisulfonimide under mild conditions to give good yields of the corresponding products. The catalyst can be easily recovered and purified for use in further reactions, which has economic and ecological advantages. Georg Thieme Verlag Stuttgart.
- Barbero, Margherita,Bazzi, Stefano,Cadamuro, Silvano,Dughera, Stefano,Piccinini, Claudia
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experimental part
p. 315 - 319
(2010/03/05)
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- One-pot hydroxy group activation/carbon-carbon bond forming sequence using a Bronsted base/bronsted acid system
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A new sequential two-step multicatalytic strategy is presented consisting in the efficient DBU-catalysed trichloroacetimidation of an alcohol followed by a ditriflylamine (Tf2NH)-catalysed intermolecular alkylation by silicon-based nucleophiles and C-H nucleophiles. The distinct feature of the trichloroacetimidate group allows use of weaker acid catalysts such as 1,1′-bi-2-naphthol (BINOL)-derived phosphoric acid, pointing out the possible development of an enantioselective variant. This unprecedented sequential one-pot Bronsted base-Bronsted acid catalysis further expands the synthetic scope of the trichloroacetimidate group. Copyright
- Devineau, Alice,Pousse, Guillaume,Taillier, Catherine,Blanchet, Jerome,Rouden, Jacques,Dalla, Vincent
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supporting information; experimental part
p. 2881 - 2886
(2011/02/21)
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- Catalytic coupling of N-benzylic sulfonamides with silylated nucleophiles at room temperature
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In the presence of 2-10 mol% of Tf2NH, a range of N-benzylic sulfonamides smoothly react with allylic, propargylic, benzylic, or hydrido silanes at room temperature via sp3 carbon-nitrogen bond cleavage to afford structurally diverse products in moderate to excellent yields and with high chemo- and regioselectivity.
- Yang, Bai-Ling,Tian, Shi-Kai
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supporting information; experimental part
p. 6180 - 6182
(2010/10/20)
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- Palladium catalyzed isomerization of alkenes: A pronounced influence of an o-phenol hydroxyl group
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A novel palladium catalyzed isomerization of alkenes has been found, where an ortho-phenol hydroxyl group has a pronounced influence on the isomerization.
- Fan, Jinmin,Wan, Changfeng,Wang, Qiang,Gao, Linfeng,Zheng, Xiaoqi,Wang, Zhiyong
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supporting information; experimental part
p. 3168 - 3172
(2011/02/25)
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- Palladium-catalyzed benzylic direct arylation of benzyl sulfones with aryl halides
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An effective palladium catalyst system for the direct arylation of benzyl sulfones with aryl halides has been developed. The catalytic reaction provides a facile route to diarylmethyl sulfones. The products can be transformed further via desulfonylative functionalization mediated by aluminum compounds.
- Niwa, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
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experimental part
p. 1971 - 1976
(2009/08/07)
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- Boron trihalide mediated substitution of hydroxyl groups with alkenyl, alkynyl, and allyl moieties
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The coupling of alcohols with alkenyl- and alkynylboron dihalides with high olefin stereoselectivity is described. The reaction provides a facile route to internal acetylenes. Notably, the allylation of propargylic alcohols mediated by boron trichloride p
- Kabalka, George,Borella, Scott,Yao, Min-Liang
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p. 325 - 329
(2008/12/21)
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- 1,3-Dilithio-2-(diphenylmethylene)propane
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The reaction of 2,2-diphenylmethylenecyclopropane (5) with an excess of lithium and a catalytic amount of DTBB (4 mol %) in THF at -78 °C leads to the formation of dilithiated species 6-8 by reductive opening of the cyclopropane ring. Further reaction of these intermediates with different electrophiles [E = H2O, D2O, CH2{double bond, long}CMeCH2Cl, Me3SiCl, Me3SiCH2Cl, t-BuCHO, Me2CO, Et2CO, n-Pr2CO, i-Pr2CO, t-Bu2CO, (CH2)5CO, Ph2CO and adamantanone] is highly regioselective, yielding exclusively the corresponding products 9, after hydrolysis with water. However, when 3-chloro-2-(chloromethyl)propene (14) is used as a dielectrophile, the cyclisation to give a six-membered ring takes place through intermediate 6, giving compound 16 as the only reaction product.
- Lillo, Victor J.,Gómez, Cecilia,Yus, Miguel
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p. 5182 - 5185
(2008/12/20)
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- Nucleophilic substitution reactions of alcohols with use of montmorillonite catalysts as solid Bronsted acids
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(Chemical Equation Presented) We have developed an environmentally benign synthetic approach to nucleophilic substitution reactions of alcohols that minimizes or eliminates the formation of byproducts, resulting in a highly atom-efficient chemical process. Proton- and metal-exchanged montmorillonites (H- and Mn+-mont) were prepared easily by treating Na +-mont with an aqueous solution of hydrogen chloride or metal salt, respectively. The H-mont possessed outstanding catalytic activity for nucleophilic substitution reactions of a variety of alcohols with anilines, because the unique acidity of the H-mont catalyst effectively prevents the neutralization by the basic anilines. In addition, amides, indoles, 1,3-dicarbonyl compounds, and allylsilane act as nucleophiles for the H-mont-catalyzed substitutions of alcohols, which allowed efficient formation of various C-N and C-C bonds. The solid H-mont was reusable without any appreciable loss in its catalytic activity and selectivity. Especially, an Al3+-mont showed high catalytic activity for the α-benzylation of 1,3-dicarbonyl compounds with primary alcohols due to cooperative catalysis between a protonic acid site and a Lewis acidic Al3+ species in its interlayer spaces.
- Motokura, Ken,Nakagiri, Nobuaki,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 6006 - 6015
(2008/02/10)
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- Deoxygenative allylation of benzyl acetates and cinnamyl alcohols catalyzed by molecular iodine
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Benzyl acetates undergo smooth deoxygenative allylation with allyltrimethylsilane in the presence of 10 mol % of molecular iodine under mild conditions to afford the corresponding allyl derivatives in excellent yields and with high selectivity. Cinnamyl alcohols also react readily with allylsilane under similar conditions. The use of molecular iodine makes this method quite simple, more convenient and cost effective. Copyright
- Yadav,Reddy, B. V. Subba,Reddy, A. Srinivas,Eeshwaraiah
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p. 1500 - 1501
(2008/03/14)
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- Regioselective cross-coupling of allylindium reagents with activated benzylic bromides-a simple and efficient procedure for the synthesis of terminal alkenes
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Allylindium reagents undergo facile and highly regioselective cross-coupling with benzylic and cinnamyl bromides in THF at room temperature without any catalyst producing terminal alkenes in high yields. The addition is highly regioselective and is found to provide γ-adducts in all reactions.
- Ranu, Brindaban C.,Banerjee, Subhash,Adak, Laksmikanta
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p. 7374 - 7379
(2008/03/13)
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- Direct coupling reaction between alcohols and silyl compounds: Enhancement of Lewis acidity of Me3SiBr using InCl3
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The combination of InCl3 and Me3SiBr provided an enhanced Lewis acid system that can be used to promote a wide range of direct coupling reactions between alcohols and silyl nucleophiles in non-halogenated solvents, such as hexane or MeCN. The enhanced Lewis acidity of this system was measured by the 13C NMR in terms of the coordination to an alcohol. Moreover, the interaction between Me3SiBr and the In(III) species was revealed by 29Si NMR spectral analysis. Highly chemoselective allylations toward a hydroxyl moiety over ketone and acetoxy ones have been demonstrated.
- Saito, Takahiro,Nishimoto, Yoshihiro,Yasuda, Makoto,Baba, Akio
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p. 8516 - 8522
(2007/10/03)
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- Direct C-allylation of aryl-alkyl/glycosyl carbinols: Facile synthesis of C-linked carbo-β2-/γ2-/δ2- amino acids
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A facile ZrCl4-catalyzed direct allylation of the p-methoxyphenyl-alkyl/glycosyl carbinols at room temperature, and the conversion of the derived aryl-glycosyl-alkenes into hitherto unknown C-linked carbo-β2-/γ2-/δ2-amino acids is reported.
- Sharma, Gangavaram V. M.,Reddy, Katta Laxmi,Lakshmi, P. Sree,Ravi,Kunwar, Ajit C.
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p. 3967 - 3969
(2007/10/03)
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