Paride Grisenti

Lipase-catalyzed transesterification in organic solvents: Applications to the preparation of enantiomerically pure compounds

Abstract Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) can be used for the synthesis of esters by transesterification with activated and nonactivated acyl donors in organic solvents. The reaction is especially useful for the preparation of optically active compounds, which are formed by resolution or asymmetrization of racemic or prochiral suitable substrates. This review offers an overview of the state of the art through examples chosen from the most recent literature, focusing mainly on the preparation of enantiomerically pure products which can be formed by this enzymatic approach.

An efficient chemo-enzymatic approach to the enantioselective synthesis of 2-methyl-1,3-propamedical derivatives

Abstract Lipase-catalyzed transesterification of 2-methyl-1,3-propanediol 1 in chloroform affords enantiomerically pure (S)-(−)-acetate 2 , from which the (R)-(+)-silyl ethers 4a-b can be efficiently prepared (>98% ee). The (S)-TBDPS derivative 4b could be also efficiently and enantioselectively prepared by the same enzymatic procedure, starting from racemic 5b .

Enantioselective transesterification of 2-methyl-1,3-propanediol derivatives catalyzed by Pseudomonas fluorescens lipase in an organic solvent

Abstract The irreversible transesterification of racemic 2-methyl-1,3-propanediol derivatives, the monoethers, 3a , 3b , 5a , and the monobenzoate 5b , with vinyl acetate catalyzed by Pseudomonas fluorescens lipase in chloroform affords enantiomerically pure chiral synthons.

Selective enzymatic transformations of itaconic acid derivatives: An access to potentially useful building blocks

Abstract Hydrolytic enzymes regioselectively catalyze the hydrolysis of diethyl itaconate 5a to the monoester 5c and opening of itaconic anhydride 6 to the regioisomeric monoester 5b that was tranformed into the hydroxy esters 2. This was used for the synthesis of β-methylene-,γ-butyrolactone 7 and of the racemic epoxyalcohol 3, that was resolved by a highly enantioselective Pseudomonas fluorescens lipase-catalyzed transesterification into (S)-3 and (S)-8 (90 and 86% ee, respectively).

Regio- and enantioselectivity of Pseudomonas cepacia lipase in the transesterification of 2-substituted-1,4-butanediols

Abstract The transesterification of 2-substituted-1,4-butanediols 1a , 2a and 3a with vinyl acetate catalyzed by the Pseudomonas cepacia lipase in organic solvents affords preferentially the 1-acetate, the highest regioselectivity having been found for the epoxydiol 3a , which is enantioselectively resolved [86% ee for the unreacted (S)-(−)- 3a ].

Baker's yeast-mediated reduction of α-hydroxy ketones and derivatives: The steric course of the biotransformation

Abstract The results from the bakers yeast-mediated reduction of the acetates 3a-d and the methyl ethers 5a-d were compared with the same biotransformation which converts the α-hydroxy ketones 1a-d into the (R)-diols 2a-d (90–98%ee); the acetates 3a-d afford the (S)-monoacetates 4a-d (72–94% ee) and the methyl ethers 5a-d are reduced to the (R)-monoethers 6a-d (64–76% ce).

Polyethylene Glycols as Solvents for Anionic Activation: Synthesis of Thioacetates by Means of Potassium Thioacetate in Polyethylene Glycol 400

Abstract Recently, polyethylene glycols (PEGS) of various molecular weights have been proposed as solvent promoters for various reactions 1, 2. We wish to report on the use of PEG 400 as solvent for the anionic activation of potassium thioacetate, which could be used for the preparation of alkyl and benzyl thioacetates from the corresponding halides or alcohol derivatives. The method can be synthetically significant, since from thioacetates the corresponding thiols can be easily prepared under a variety of mild conditions 3.

Biocatalytic, Enantioselective Preparations of (R)- and (S)-Ethyl 4-Chloro-3-Hydroxybutanoate, a Useful Chiral Synthon

The synthesis of optically active ethyl 4-chloro-3-X-butanoate derivatives la-d (X = OH, a; OCOCH3, b; OCOC3H7, c; OCH2C6H5, d) was realized using various biocatalytic approaches such as microbiological reduction of ethyl 4-chloro-3-oxobutanoate 2 with lactic acid bacteria, hydrolysis of lb-d by the hydrolytic enzymes PLE and BChE and the transesterification of la catalyzed by a lipase from Pseudomonas fluorescens (PFL).

An Insight into the Active Site of Pseudomonas Fluorecens (P. cepacia) Lipase to Define the Stereochemical Demand for the Transesterification in Organic Solvents

The Pseudomonas fluorescens lipase-catalyzed transesterification of 2-methyl alkanols 1 and the 2-substituted oxiranemethanols 2 with vinyl acetate in organic solvents has been studied and the results discussed in terms of steric and electronic demand within the recently postulated models of the lipase active site.

Studies on the enantioselectivity of the transesterification of 2-methyl-1,4-butanediol and its derivatives catalyzed by Pseudomonas fluorescens lipase in organic solvents

Abstract The irreversible transesterification of 2-methyl-1,4-butanediol 1a and its benzyl ethers 2a and 3a catalyzed by Pseudomonas fluorescens lipase in chloroform was studied, the highest ee (>98%) having been obtained for the 4-benzyl ether 2a .