Rosario Brieva

Lipase catalyzed aminolysis of ethyl propiolate and acrylic esters. Synthesis of chiral acrylamides

Abstract Candida cylindracea lipase is a useful catalyst for the preparation of propiolamides. Candida antarctica lipase efficiently catalyzes the aminolysis of different acrylic esters and aliphatic amines; if racemic amines are used, the corresponding optically active acrylic amide is obtained in moderate-high enentiomeric excess.

Enzymatic aminolysis and transamidation reactions

Abstract Chiral amides obtained from (±)-2-chloropropionate esters and a wide range of amines when the reaction is catalysed by Candida cylidracea lipase. The enantioselection of the enzyme in this aminolysis reaction depends on the substrate and nucleophile structure and reaction conditions. This lipase can catalyze a transamidation reaction if N-trifluoroethyl-2-chloropropionamide is used as substrate. In this way, amides are obtained in high-moderate enantiomeric excesses. The aminolysis of ethyl (±)-2-methylbutyrate with aliphatic amines is achieved using CC and PS lipases as catalysts.

CHEMOENZYMATIC SYNTHESIS OF (S)-2-CYANOPIPERIDINE, A KEY INTERMEDIATE IN THE ROUTE TO (S)-PIPECOLIC ACID AND 2-SUBSTITUTED PIPERIDINE ALKALOIDS

Abstract The preparation of ( S )-2-cyanopiperidine 4 provides a new access to 2-substituted piperidines. This synthesis is based on an enantioselective ( R )-oxynitrilase-catalyzed reaction for the preparation of ( R )-(+)-6-bromo-2-hydroxyhexanenitrile 1 and the subsequent cyclization of this compound to yield the piperidine ring. The utilization of 4 as the starting material for the synthesis of ( S )-2-aminomethylpiperidine 6 , ( R )-(−)-coniine 10 and ( S )-(−)-pipecolic acid 13 is also described.

Lipase-catalyzed synthesis of optically active amides in organic media

Abstract Lipases from Candida cylindracea and Candida antarctica catalyze the aminolysis of activated and nonactivated esters respectively. The degree of enantioselectivity depends on the amine.

Enzymatic resolution of (±)-6-(5-chloropyridin-2-yl)-6-vinyloxy-carbonyloxy-6,7-dihydro[5H]pyrrolo[3,4-b]pyrazin-5-one. Synthesis of (+)-zopiclone

Abstract The lipase from Candida antarctica (CAL) catalyzes the resolution of a precursor of zopiclone through hydrolysis and transcarbonatation processes.

Chemoenzymatic synthesis of azacycloalkan-3-ols

Abstract Optically active ω-bromocyanohydrins are easily synthesized through an enantioselective ( R )-oxynitrilase-catalyzed reaction from their corresponding ω-bromoaldehydes. These cyanohydrins are starting materials for the preparation of medium size nitrogen heterocycles. The reduction of ( R )-(+)-5-bromo-2-hydroxypentanenitrile affords, in one-pot, piperidin-3-ol. Azepan-3-ol and azocan-3-ol are readily obtained from their corresponding cyanohydrins in high enantiomeric excesses.

Optically active (S)-ketone- and (R)-aldehyde-cyanohydrins via an (R)-oxynitrifase-catalysed transcyanation. Chemoenzymatic syntheses of 2-cyanotetrahydrofuran and 2-cyanotetrahydropyran

(R)-Oxynitrilase catalyses the enantioselective decyanation of racemic ketone cyanohydrins and the enantioselective addition of HCN to ω-bromoaldehydes in one step.

A simple procedure for the preparation of chiral amides

Abstract Yeast lipase ( Candida cylindracea ) catalysed the reaction between ethyl (±)-2-chloropropionate and different aliphatic and aromatic amines yielding optically active amides.

Enzymatic resolution of new carbonate intermediates for the synthesis of (S)-(+)-zopiclone

Abstract The lipase from Candida antarctica B catalyzes the enantioselective hydrolysis of (±)-6-(5-chloropyridin-2-yl)-7-chloromethyloxycarbonyloxy-6,7-dihydro-5H-pyrrolo[3,4-b]pyrazin-5-one, a useful intermediate in the synthesis of (S)-(+)-zopiclone. This enzyme also catalyzes the resolution of the corresponding 2-chloroethylcarbonate derivative.

Stereocontrolled chemoenzymatic synthesis of 2,3-disubstituted piperidines

Abstract ( R,R )-2,3-Disubstituted piperidines were readily synthesized starting from ( R )-(+)-5-bromo-2-hydroxypentanenitrile ( R )- 2 . An enantioselective ( R )-oxynitrilase-catalyzed transcyanation was used to prepare the starting cyanohydrin ( R )- 2 .