- Two-way homologation of aliphatic aldehydes: Both one-carbon shortening and lengthening via the same intermediate
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Aliphatic aldehydes can be homologated to both one-carbon shorter and one-carbon longer homologous carbonyl compounds through the 2–4 steps of reactions via the same intermediates, β,γ-unsaturated α-nitrosulfones, prepared from the proline-catalyzed sequential reactions of several aliphatic aldehydes with phenylsulfonylnitromethane. While the oxidative cleavage of the key intermediates gave one-carbon less homologous carbonyl compounds, the reduction of the same key intermediates followed by an oxidation produced one-carbon more homologous carbonyl compounds.
- Yoo, Jae Won,Seo, Youngran,Park, Jong Beom,Kim, Young Gyu
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- Phosphine-ligated Ir(III)-complex as a bi-functional catalyst for one-pot tandem hydroformylation-acetalization
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The complexation of IrCl3?3H2O with the electron-deficient phosphines (L1-L6) respectively afforded a bi-functional catalyst possessing the dual functions of transition metal complex (IrIII-P) and IrIII-Lewis acid for tandem hydroformylation-acetalization of olefins. The best result was obtained over L5-based IrCl3?3H2O catalytic system which corresponded to 97% conversion of 1-hexene along with 92% selectivity to the target acetals free of any additive. The crystal structure of the novel IrIII-complex of IrIII-L4 indicated that the electron-deficient nature of the involved phosphine warranted Ir-center in +3 valence state without reduction, which served as the Lewis acid catalyst for the subsequent acetalization of the aldehydes as well. Moreover, as an ionic phosphine, L6-based IrCl3?3H2O system immobilized in RTIL of [Bmim]PF6 could be recycled for 6 runs without the obvious activity loss or metal leaching.
- Liu, Huan,Liu, Lei,Guo, Wen-Di,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 215 - 221
(2019/04/17)
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- Phosphonium-based aminophosphines as bifunctional ligands for sequential catalysis of one-pot hydroformylation-acetalization of olefins
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A series of ionic phosphonium-based aminophosphines L1-L3 were prepared and fully characterized, in each of which the involved bifunctional moieties of the phosphine fragment and Lewis acidic phosphonium were linked together by stable chemical bonds and bridged by one N-atom. The molecular structure of the L2-ligated Rh-complex (Rh-L2) indicated that such bifunctionalities were well retained without incompatibility problems. Investigations on co-catalysis over L1-L3 showed that L3 exhibited the best sequential catalysis for both hydroformylation and acetalization. The phosphine fragment in L3 was responsible for hydroformylation together with the Rh-complex and the phosphonium acted as the Lewis acidic catalyst in charge of acetalization. The L3-Rh(acac)(CO)2 system also exhibited good generality to hydroformylation-acetalization of a wide range of olefins in different alcohols.
- Wang, Peng,Liu, Huan,Li, Yong-Qi,Zhao, Xiao-Li,Lu, Yong,Liu, Ye
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p. 3854 - 3861
(2016/06/14)
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- Hypoiodous acid-catalyzed regioselective geminal addition of methanol to vinylarenes: synthesis of anti-Markovnikov methyl acetals
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A novel metal-free, catalytic geminal dimethoxylation of vinylarenes based on in situ generated HOI species from iodide salt and oxone is reported. The preliminary mechanistic investigations suggest that the key factor for achieving the anti-Markovnikov regioselectivity is the semipinacol rearrangement of an iodo functionalized intermediate, which is confirmed by an isotope labeling experiment. In addition, the reaction involves the de-iodination of a co-iodo intermediate via its oxidation to hypervalent iodine species rather than a common iodide abstraction by electrophiles. The HRESI-MS studies support the conversion of monovalent iodine containing intermediates to trivalent iodine intermediates during the catalytic conversion of aromatic alkenes into the corresponding terminal acetals.
- Peraka, Swamy,Mameda, Naresh,Marri, Mahender Reddy,Kodumuri, Srujana,Chevella, Durgaiah,Sripadi, Prabhakar,Nama, Narender
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p. 73732 - 73736
(2015/09/15)
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- Selective hydroformylation-acetalization of various olefins using simple and efficient Rh-phosphinite complex catalyst
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A simple and efficient Rh-phosphinite complex catalyst was studied for the selective hydroformylation of various olefins. The influence of various reaction parameters including the effect of temperature, pressure, catalyst loading, time, and solvents was studied. The protocol was also applied for the synthesis of various acetals via tandem hydroformylation-acetalization of olefins in alcohols as solvents. High activity and selectivity for acetal formation was achieved in the absence of co-catalysts with admirable substrate to catalyst mole ratio (TON 2500). The developed protocol works for a wide range of olefins to synthesize corresponding aldehydes and acetals under optimized reaction conditions.
- Khan, Shoeb R.,Bhanage, Bhalchandra M.
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p. 5998 - 6001
(2013/10/22)
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- Highly effective tandem hydroformylation-acetalization of olefins using a long-life Bronsted acid-Rh bifunctional catalyst in ionic liquid-alcohol systems
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A robust and highly effective tandem hydroformylation-acetalization of olefins using a Bronsted acid-Rh bifunctional catalyst (ARBC) in ionic liquid-alcohol systems is reported. The key feature of the ARBC is its use of a zwitterionic phosphine ligand bearing an amino acid tag. This novel ARBC shows an excellent catalytic efficiency and a long service life without a significant drop in both the hydroformylation efficiency and the acetalization efficiency or Rh loss for more than seventeen cycles. We believe that the long-term high activity and acetal selectivity mainly benefit from the synergy between the acidic active site and the Rh active site on the ARBC and the highly effective immobilization and recycling of ARBC in ionic liquid-alcohol systems due to the strong affinity of ARBC for the ionic liquid.
- Jin, Xin,Zhao, Kun,Cui, Feifei,Kong, Fangfang,Liu, Qiangqiang
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p. 3236 - 3242
(2013/11/06)
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- A generalized approach for iron catalyzed chemo- and regioselective formation of anti-Markovnikov acetals from styrene derivatives
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Fe(BF4)2·6H2O in the presence of pyridine-2,6-dicarboxylic acid and PhI(OAc)2 can efficiently catalyze the formation of chemoselective dialkyl acetals from styrene derivatives with anti-Markovnikov regioselectivity in good to high yields under mild and benign reaction conditions.
- Chowdhury, Abhishek Dutta,Lahiri, Goutam Kumar
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supporting information; experimental part
p. 3448 - 3450
(2012/05/20)
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- Method for the selective formation of dimethyl acetals in the presence of hydroxylamine
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An inexpensive and mild method for the formation of dimethyl acetals from the corresponding aldehydes is achieved using hydroxylamine and methanol under neutral conditions at room temperature. Notably, the reaction is selective for aldehydes in the presence of ketones, rendering this an example of a chemoselective acetalization. For saturated, sterically accessible aldehydes, catalytic amounts of hydroxylamine may be employed to attain the corresponding dimethyl acetal as the sole product in good to excellent yield. Unsaturated and hindered aldehydes required stoichiometric amounts of hydroxylamine but provided dimethyl acetals as the major product in typically excellent yield. In some cases, the corresponding oxime was also observed but may be separated from the acetal by flash column chromatography or distillation. The involvement of an intermediate oxime compound is postulated. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file. Taylor & Francis Group, LLC.
- Mickelsen, Ky J.,Tajc, Chelsea M.,Greenwood, Kevin R.,Browder, Cindy C.
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experimental part
p. 186 - 194
(2011/10/31)
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- A new scandium metal organic framework built up from octadecasil zeolitic cages as heterogeneous catalyst
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Zeolitic cages of the AST type are found in the novel scandium-squarate MOF, and the joining of them gives rise to a new binodal network with a unique topology; this new material is an efficient heterogeneous Lewis acid catalyst. The Royal Society of Chemistry 2009.
- Gandara, Felipe,Gomez-Lor, Berta,Iglesias, Marta,Snejko, Natalia,Gutierrez-Puebla, Enrique,Monge, Angeles
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supporting information; experimental part
p. 2393 - 2395
(2009/09/06)
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- Epoxide ring-opening and Meinwald rearrangement reactions of epoxides catalyzed by mesoporous aluminosilicates
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Mesoporous aluminosilicates efficiently catalyze the ring-opening of epoxides to produce β-alkoxyalcohols in high yields under extremely mild reaction conditions. These materials also catalyze the corresponding Meinwald rearrangement in non-nucleophilic solvents to give aldehydes which can be trapped in situ to provide the corresponding acetals in an efficient tandem process. The Royal Society of Chemistry 2009.
- Robinson, Mathew W. C.,Davies, A. Matthew,Buckle, Richard,Mabbett, Ian,Taylor, Stuart H.,Graham, Andrew E.
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experimental part
p. 2559 - 2564
(2009/10/30)
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- IPy2BF4-mediated rearrangements of 1,2-difunctionalized compounds and olefins
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Acetal derivatives are easily obtained from 1,2-difunctionalized compounds by a new reaction mediated by IPy2BF4 with a mechanism based on a 1,2-migration of aryl or alkyl groups. A new oxidative rearrangement reaction of olefins is also described. Moreover, when this metal-free protocol is applied to cyclic olefins, interesting ring-contraction reactions are observed. The new methodologies described here are a clean and efficient alternative to known strategies that make use of potentially toxic metallic complexes.
- Fananas, Francisco J.,Alvarez-Perez, Monica,Rodriguez, Felix
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p. 5938 - 5944
(2007/10/03)
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- The Heck-type arylation of allylic alcohols with arenediazonium salts
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The Heck coupling of ArN2BF4 with secondary allylic alcohols, carried out in methanol using Pd(dba)2 as catalyst without extra ligands and base, leads to the corresponding β-arylated carbonyl compounds. Such conditions afford arylated acetals from primary allylic alcohols.
- Masllorens, Judit,Bouquillon, Sandrine,Roglans, Anna,Hénin, Fran?oise,Muzart, Jacques
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p. 3822 - 3826
(2007/10/03)
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- SO3H-functionalized silica for acetalization of carbonyl compounds with methanol and tetrahydropyranylation of alcohols
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Sulfonic acid group-functionalized amorphous silica acts as a highly effective and reusable catalyst for acetalization of various carbonyl compounds with methanol and tetrahydropyranylation of alcohols.
- Shimizu, Ken-Ichi,Hayashi, Eidai,Hatamachi, Tsuyoshi,Kodama, Tatsuya,Kitayama, Yoshie
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p. 5135 - 5138
(2007/10/03)
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- Use of delaminated zeolites (ITQ-2) and mesoporous molecular sieves in the production of fine chemicals: Preparation of dimethylacetals and tetrahydropyranylation of alcohols and phenols
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The combination of zeolitic acidities, easy reactant accessibility, and fast desorption-diffusion of products are determinant issues for designing successful catalysts for acid-catalyzed reactions in the field of fine chemicals production. Protection of aldehydes by formation of the corresponding dimethyl acetals and of alcohols and phenols by formation of the corresponding tetrahydropyranyl ethers were performed using ITQ-2 zeolite as acid catalyst. Its catalytic activity for these reactions was compared with those obtained with MCM-22, Beta zeolites, and the mesoporous aluminosilicate MCM-41, all with similar Si/Al ratios. When the reactions involved bulky reactants, ITQ-2 showed, in all cases, the highest activity as a consequence of the combination of its delaminated structure and the presence of strong acid sites. The zeolitic nature of the acid sites present in the delaminated ITQ-2 zeolite made the acid sites more stable than those present in the short range amorphous MCM-41 molecular sieve, providing the former catalyst better activity and thermal regenerability. ITQ-2 and MCM-41 are active and selective catalysts for acetalization reactions involving reactants as large as diphenylacetaldehyde and cholesterol.
- Corma,Rodriguez,Climent,Iborra,Fornes
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p. 441 - 447
(2007/10/03)
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- Use of mesoporous MCM-41 aluminosilicates as catalysts in the production of fine chemicals: Preparation of dimethylacetals
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Dimethylacetals have been prepared by reacting aldehydes with trimethyl orthoformate. Large pore zeolites (HY and beta) as well as mesoporous silica-aluminas with regular pore sizes, such as MCM-41 and SAM, and commercial amorphous silica-alumina with a broader distribution of pore sizes have been used as catalysts. The results indicate that in addition to bridging hydroxyl groups, silanols can also be active for carrying out this reaction. Zeolites are more active than the mesoporous materials, but their activity decays faster. By carrying out the reaction with aldehydes of different molecular sizes it is shown that the MCM-41 mesoporous materials are promising catalysts for their use in the production of fine chemicals which involve bulky reactants or products. Finally, mesoporous catalysts with a very narrow pore size distribution show a better catalytic behavior than others with a broader pore size distribution.
- Climent,Corma,Iborra,Navarro,Primo
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p. 783 - 789
(2007/10/03)
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- Copper-Mediated Oxygenation of Aldehydes and Internal Cannizzaro-like Rearrangement of Phenylglyoxal
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Under the influence of Cu(II) in MeOH containing py and Et3N, PhCH2CHO undergoes competitive O2-dependent conversions to PhCHO and phenylglyoxal.The latter, as the MeOH hemiacetal, undergoes a Cu(II)-catalyzed rearrangement to PhCHOHCOOMe and a Cu(II) oxidation to PhCOCOOMe, and there appears to be independent O2-mediated production of PhCOCOOH.Phenylglyoxal also undergoes oxidative cleavage to PhCOOH, but does not give rise to PhCHO.The homologous aldehyde PhCH2CH2CHO is converted mainly via PhCH2CHO to a product mixture derived from the latter.This result is interp reted in terms of preferential C-C cleavage of an α-hydroxyperoxide intermediate initially formed from PhCH2CH2CHO.The alternative pathway for this intermediate, dehydration to α-keto aldehyde PhCH2COCHO, is barely competitive, because the independently prepared α-keto aldehyde gives a distinct set of products under the reaction conditions.The preference for cleavage over dehydration explains the previously published finding of a stepwise degradation of long-chain aldehydes to formate units by the Cu(II)-py-Et3N-MeOH-O2 system.Product comparisons using either an O2 atmosphere or a N2 atmosphere (with varying equivalents of CuII) permit a distinction between stoichiometric Cu(II) oxidations and O2-dependent reactions.Mechanism are proposed for the observed transformations.
- Jin, Shiow-Jen,Arora, Pramod K.,Sayre, Lawrence M.
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p. 3011 - 3018
(2007/10/02)
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- On the Mechanism of Lewis Acid Mediated Nucleophilic Substitution Reactions of Acetals
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Lewis acid mediated nucleophilic substitution of acetals can occur by direct displacement (SN2) or oxocarbenium ion (SN1) mechanisms.With acyclic acetals, stereoselectivity increases with increasing steric bulk of the alkoxy group and with increasing polarity of the reaction medium.The enhanced stereoselectivity observed with acetals of secondary and tertiary alcohols is explained by perturbation of the approach trajectory of the nucleophilic alkene as it attacks the oxocarbenium ion.Highest stereoselectivity is seen in the reaction of 2-(1-phenylethyl)-4,4,5,5-tetramethyl-1,3-dioxolane (4) with enol silane 5; only one diastereomeric product (9s) is obtained, even in the relatively nonpolar solvent CH2Cl2.The TiCl4-mediated reactions of cyclic acetals 18c, 18t, 25, and 28 with silyl enol ether 5 show that in these systems the substitution does not occur by the SN2 mechanism.
- Mori, Ichiro,Ishihara, Kazuaki,Flippin, Lee A.,Nozaki, Kyoko,Yamamoto, Hisashi,et al.
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p. 6107 - 6115
(2007/10/02)
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- ELECTROOXIDATIVE REARRANGEMENT OF CONJUGATED ARYLOLEFINS TO ARYLACETALDEHYDE DIMETHYL ACETALS
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Electrochemical oxidation of conjugated arylolefins 1 in trimethyl orthoformate containing iodine gave arylacetaldehyde dimethyl acetals 2 in high yields.
- Shono, Tatsuya,Matsumura, Yoshihiro,Katoh, Susumu,Ikeda, Kaoru,Fujita, Tetsuhiro,Kamada, Tohru
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p. 5309 - 5312
(2007/10/02)
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- METHOXYCHLORINATION AND DIMETHOXYLATION OF ALKENES. THE REACTIONS OF SUBSTITUTED STYRENES WITH PHENYLSELENENYL CHLORIDE IN METHANOL
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The addition of PhSeCl to α- and β-substituted styrenes in methanol is regio- and stereospecific and affords the products of methoxyselenenylation.These compounds further react with PhSeCl to give the deselenenylation products.In the case of α-substituted styrenes, 1-methoxy, 2-chloroalkanes are produced, whereas with β-substituted styrenes the major reaction products are the 1,2-dimethoxyalkanes and the 2,2-dimethoxyalkanes in which phenyl migration has occured.It is shown that these reactions proceed through the intermediate formation of the alkyl phenylselenium dichlorides, PhCR(OMe)CHR1SeCl2Ph, which evolve with different mechanisms depending on the structure of the starting alkenes.
- Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Bartoli, Donatella
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p. 2261 - 2272
(2007/10/02)
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- A Convenient Method for the Preparation of Secondary Propargylic Ethers. The Reaction of Acetals with 1-Trimethylsilyl-1-alkynes Promoted by the Combined Use of Catalytic Amounts of Tin(IV) Chloride and Zinc Chloride
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In the coexistence of catalytic amounts of SnCl4 and ZnCl2, acetals undergo a coupling with 1-trimethylsilylalkynes to give secondary propargilic ethers in good yields.Similarly, propargilic ethers are directly produced from aldehydes by the treatment with alkoxytrimethylsilanes and 1-trimethylsilylalkynes under the same conditions.This catalyst system also efficiently promotes aldol reaction of silyl enol ethers with acetals or aldehydes, and the Michael reaction of silyl enol ethers with α,β-unsaturated ketones.
- Hayashi, Masaji,Inubushi, Atsuro,Mukaiyama, Teruaki
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p. 4037 - 4042
(2007/10/02)
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- A Simple and Efficient Conversion of Aldehyde Acetals into Esters
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The reaction of aldehydic acetals with hypochlorous acid in acetic acid-acetone afforded the corresponding esters in excellent yields.From cyclic acetals, only the corresponding hydroxyalkyl esters were obtained.Keywords - acetal; hypochlorite; hypochlorous acid; conversion; ester; hydroxyalkyl ester; regioselectivity
- Sugai, Saburo,Kodama, Takashi,Akaboshi, Sanya,Ikegami, Shiro
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