7226-82-6Relevant academic research and scientific papers
Kinetic Resolution of Allylic Alcohol with Chiral BINOL-Based Alkoxides: A Combination of Experimental and Theoretical Studies
Liu, Yidong,Liu, Song,Li, Dongmei,Zhang, Nan,Peng, Lei,Ao, Jun,Song, Choong Eui,Lan, Yu,Yan, Hailong
supporting information, p. 1150 - 1159 (2019/01/11)
The development and characterization of enantioselective catalytic kinetic resolution of allylic alcohols through asymmetric isomerization with chiral BINOL derivatives-based alkoxides as bifunctional Br?nsted base catalysts were described in the study. A number of chiral BINOL derivatives-based alkoxides were synthesized, and their structure-enantioselectivity correlation study in asymmetric isomerization identified a promising chiral Br?nsted base catalyst, which afforded various chiral secondary allylic alcohols (ee up to 99%, S factor up to >200). In the mechanistic study, alkoxide species were identified as active species and the phenol group of BINOL largely affected the high reactivity and enantioselectivity via hydrogen bonding between the chiral Br?nsted base catalyst and substrates. The strategy is the first successful synthesis strategy of various chiral secondary allylic alcohols through enantioselective transition-metal-free base-catalyzed isomerization. The applicability of the strategy had been demonstrated by the synthesis of the bioactive natural product (+)-veraguensin.
Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
Chen, Peiran,Yang, Wenhong
supporting information, p. 2290 - 2294 (2014/04/17)
By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
Carboxylation with CO2 via brook rearrangement: Preparation of α-hydroxy acid derivatives
Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
, p. 14 - 17 (2014/01/23)
In the presence of CsF, a wide range of α-substituted α-siloxy silanes were carboxylated under a CO2 atmosphere (1 atm) via Brook rearrangement. A variety of α-substituents including aryl, alkenyl, and alkyl groups were tolerated to afford α-hydroxy acids in moderate-to-high yields. One-pot synthesis from aldehydes using PhMe2SiLi and CO 2 was also possible, providing α-hydroxy acids without the isolation of an α-hydroxy silane.
A new class of versatile chiral-bridged atropisomeric diphosphine ligands: Remarkably efficient ligand syntheses and their applications in highly enantioselective hydrogenation reactions
Qiu, Liqin,Kwong, Fuk Yee,Wu, Jing,Lam, Wai Har,Chan, Shusun,Yu, Wing-Yiu,Li, Yue-Ming,Guo, Rongwei,Zhou, Zhongyuan,Chan, Albert S. C.
, p. 5955 - 5965 (2007/10/03)
A series of chiral diphosphine ligands denoted as PQ-Phos was prepared by atropdiastereoselective Ullmann coupling and ring-closure reactions. The Ullmann coupling reaction of the biaryl diphosphine dioxides is featured by highly efficient central-to-axial chirality transfer with diastereomeric excess >99%. This substrate-directed diastereomeric biaryl coupling reaction is unprecedented for the preparation of chiral diphosphine dioxides, and our method precludes the tedious resolution procedures usually required for preparing enantiomerically pure diphosphine ligands. The effect of chiral recognition was also revealed in a relevant asymmetric ring-closure reaction. The chiral tether bridging the two aryl units creates a conformationally rigid scaffold essential for enantiofacial differentiation; fine-tuning of the ligand scaffold (e.g., dihedral angles) can be achieved by varying the chain length of the chiral tether. The enantiomerically pure Ru- and Ir-PQ-Phos complexes have been prepared and applied to the catalytic enantioselective hydrogenations of α- and β-ketoesters (C=O bond reduction), 2-(6′-methoxy- 2′-naphthyl)-propenoic acid, alkyl-substituted β-dehydroamino acids (C=C bond reduction), and N-heteroaromatic compounds (C=N bond reduction). An excellent level of enantioselection (up to 99.9% ee) has been attained for the catalytic reactions. In addition, the significant ligand dihedral angle effects on the Ir-catalyzed asymmetric hydrogenation of N-heteroaromatic compounds were also revealed.
Catalytic, enantioselective α-additions of isocyanides: Lewis base catalyzed Passerini-type reactions
Denmark, Scott E.,Fan, Yu
, p. 9667 - 9676 (2007/10/03)
The generality of catalytic, enantioselective α-additions of isocyanides to aldehydes has been demonstrated (Passerini-type reactions). The catalytic system of silicon tetrachloride and a chiral bisphosphoramide (R,R)-1b provided high yields and good to excellent enantioselectivities for the addition of tert-butyl isocyanide to a wide range of aldehydes (aromatic, heteroaromatic, olefinic, acetylenic, aliphatic). Aqueous workup afforded the α-hydroxy tert-butyl amides whereas a low-temperature methanol quench followed by basic workup afforded the α-hydroxy methyl esters. The reaction is also successful for other isocyanides, albeit with reduced enantioselectivity. Reaction conditions, particularly the rate of addition of the isocyanide was found to be crucial for good yields and high selectivities.
The first catalytic, asymmetric α-additions of isocyanides. Lewis-base-catalyzed, enantioselective Passerini-type reactions
Denmark, Scott E.,Fan, Yu
, p. 7825 - 7827 (2007/10/03)
The first, catalytic, enantioselective α-additions of isocyanides to aldehydes have been demonstrated (Passerini-type reactions). The catalytic system of silicon tetrachloride and a chiral bisphosphoramide 5a provided high yields and good to excellent enantioselectivities for the addition of tert-butyl isocyanide to a wide range of aldehydes (aromatic, olefinic, acetylenic, aliphatic). Aqueous workup afforded the α-hydroxy tert-butyl amides, whereas methanolic quench followed by basic workup afforded the ∞-hydroxy methyl esters. Copyright
Biocatalytic deracemisation of α-hydroxy esters: High yield preparation of (S)-ethyl 2-hydroxy-4-phenylbutanoate from the racemate
Chadha, Anju,Baskar, Baburaj
, p. 1461 - 1464 (2007/10/03)
Biocatalytic deracemisaton of the racemic ethyl ester of 2-hydroxy-4-phenylbutanoic acid gives the (S)-enantiomer exclusively in >99% e.e. and 85-90% yield. Ethyl and methyl esters of mandelic acid and the methyl ester of 2-hydroxy-4-phenylbutanoic acid also gave the (S)-enantiomer exclusively. Whole cells of Candida parapsilosis (ATCC 7330) were used to effect this biotansformation.
Lithiated dimethoxymethyl diphenyl phosphine oxide, a versatile formiate carbanion equivalent
Monenschein, Holger,Brünjes, Marco,Kirschning, Andreas
, p. 525 - 527 (2007/10/03)
Aldehydes are homologated to the corresponding α-hydroxy methyl esters using lithiated dimethoxymethyl diphenyl phosphine oxide. The primary addition product of this Horner-Wittig process collapses to the corresponding α-hydroxy ester under proton-catalyzed conditions.
1-Chloroalkyl p-Tolyl Sulfoxides as Useful Agents for Homologation of Carbonyl Compounds: Conversion of Carbonyl Compounds to α-Hydroxy Acids, Esters, and Amides and α,α'-Dihydroxy Ketones
Satoh, Tsuyoshi,Onda, Ken-ichi,Yamakawa, Koji
, p. 4129 - 4134 (2007/10/02)
One-carbon homologation of carbonyl compounds to α-hydroxy acids, esters, and amides by the use of 1-chloroalkyl p-tolyl sulfoxide as a hydroxycarbonyl anion equivalent is reported.Oxidation of the vinyl chlorides, the intermediates of the above-mentioned
