Asymmetric synthesis using chiral lithium alkoxytrialkylaluminates: obtention of (2S)-2-hydroxy-2-phenyl-4-methylpentanoic acid with 85% optical purity
PLE catalyzed hydrolyses of α-substituted α-hydroxy esters: The influence of the substituents.
作者:Henk Moorlag、Richard M. Kellogg
DOI:10.1016/s0957-4166(00)86125-x
日期:1991.1
The enzymatic hydrolyses of a variety of α-substituted mandelic and lactic esters using pig liver esterase (PLE) have been investigated. High to moderate enantioselectivity was found for various α-substituted mandelic esters, whereas PLE showed low to no enantioselectivity for α-substituted lactic esters. We observed that the enantioselectivity of PLE depends strongly on the length and nature of the
Synthese D'α-hydroxyacides optiquement actifs par addition d'organozinciques sur le phenylglyoxalate de (−) menthyle
作者:G. Boireau、A. Deberly、D. Abenhaïm
DOI:10.1016/s0040-4020(01)89110-9
日期:1989.1
organozinciques obtenus par échange in situ entre un réactif de Grignard et une solution de ZnCl2 ou ZnBr2 dans le diéthyléther ou le THF, s'additionnent sélectivement au carbonyle du phénylglyoxalate de (−) menthyle. Une variété d'acides mandéliques α-substitués deconfigurationsabsolues connues sont ainsi obtenus avec de bons rendements et, dans la marjorité des cas, une bonne induction asymétrique.
Isomannide and isosorbide as new chiral auxiliaries for the stereoselective synthesis of tertiary α-hydroxy acids
作者:André Loupy、Daphné A Monteux
DOI:10.1016/s0040-4020(02)00024-8
日期:2002.2
isosorbide are selectively protected to provide new chiralauxiliaries suitable for the preparation of enantiopure tertiary α-hydroxyacids. Diastereoselective additions of organozinc reagents on the derived phenylglyoxylates afford the desired α-hydroxyacids with 60–99% ee after saponification. Both absolute configurations of the α-hydroxyacids can be accessed, by adapted choice of either the starting
New cyclohexyl-based chiral auxiliaries: Enantioselective synthesis of α-hydroxy acids
作者:Deevi Basavaiah、Peddinti Rama Krishna
DOI:10.1016/0040-4020(95)00771-y
日期:1995.10
2R)-2-(4-tert-Butylphenoxy)cyclohexan-1-ol (5) and (1R,2R)-2-(4-phenylphenoxy)cyclohexan-1-ol (6) have been used for the first time as chiralauxiliaries. Addition of alkylzinc chlorides to the corresponding glyoxylates 5a, 6a, after hydrolysis, provided (R)-α-hydroxy acids in high optical purities.