Zuyi Li

Novozym-435-catalyzed enzymatic separation of racemic propargylic alcohols. A facile route to optically active terminal aryl propargylic alcohols

Novozym-435 (a form of Candida antarctica lipase B) was found to be an effective biocatalyst for the kinetic resolution of a variety of racemic terminal aryl propargylic alcohols affording highly optically active (S)-propargylic alcohols and (R)-propargylic alcohol acetates in high yields and good ees. The advantages of this reaction are the easy availability of starting materials and the biocatalyst, simple reaction conditions, easy operation and high stereoselectivity.

Kinetic resolution of hydroxyalkanephosphonates catalyzed by candida antarctica lipase B in organic media

A series of hydroxyalkanephosphonates were studied as substrates for CALB catalyzed acetylation with emphasis on enantioselectivity and chemical structure of substrates. Some hydroxyalkanephosphonates could be resolved successfully to give both (R)- and (S)-isomers with high enantiomeric excess.

Candida rugosa lipase-catalyzed enantioselective hydrolysis in organic solvents. Convenient preparation of optically pure 2-hydroxy-2-arylethanephosphonates

A convenient enzymatic method is presented for the preparation of optically pure 2-hydroxy-2-arylethanephosphonates. It is proved that 2-butyryloxy-2-arylethanephosphonates can be enantioselectively hydrolyzed in diisopropyl ether equilibrated with water to give both isomers in high yield and excellent enantiomeric excess.

Stereoselective synthesis of phosphorus analogs of (R)-Carnitine and (R)-GABOB

Bioreduction of 3-substituted-2-oxoalkanephosphonates by bakers yeast afforded corresponding 2-hydroxy-alkanephosphonates in good yields and ee value. These compounds ( 2a,b ) could serve as useful chirons for the stereoselective synthesis of phosphorus analogs of (R)-Carnitine and (R)-GABOB.

Biocatalytical Kinetic Resolution of Hydroxyalkanephosphonates

Chiral hydroxyalkanephosphonic acids have received significant attention in recent years due to their potential biological activities and applications as chiral synthon in natural products synthesis. As found by us, a large number of ketoand diketo-phosphonates could be converted easily by baker’s yeast to chiral hydroxyalkanephosphonates in good yield and ee value with excellent regioand stereoselectivity depending on the nature of substituents located closed to carbonyl group. Unfortunately, 1-oxyalkanephosphonates resisted to such bioreductive system. In this article, a biocatalytical kinetic resolution of 1-hydroxyalkanephosphonates by Candida antartica lipase B (CALB) was reported. Our experimental data demonstrated that 1-hydroxyethanephosphonate underwent catalytic acylation with vinyl acetate as acyl donor in organic solvent using CALB as catalyst provided both (S)acylhydroxyethanephosphonate and (R)hydroxyethanephosphonate with 87–98% ee value. Under optimized conditions, (S)hydroxycomponent was exclusively acylated almost in quantitative yield.

Yeast-Mediated Regio- and Stereoselective Reduction of Dialkyl 2,4-Dioxy-4-substituted Butanephosphonates

A series of phosphorus-based carbonyl compounds, namely, dialkyl 2,4dioxy-4-substituted butane phosphonates (1), was prepared by reaction of carbanion resulted from 2-methyl-2-oxoethane phosphonate with substituted acetates. Bioreduction of 1 by baker’s yeast at 30◦C for 24–48 h usually offered an isomeric mixture); when R1 is methyl, the isomeric mixture of 2 and 3 in 45 and 24 yield as well as 92% and 80% ee value respectively. It is interesting to note that when R2 is CF3 or C3F7, a regioand stereoselective reduction was observed. Thus, only 2 was obtained in 54–67% yield and 90–94% ee value.