Ethyl butyryl oxy(phenyl)methane(P-phenyl)phosphinate was hydrolyzed using four bacterial species as biocatalysts. In all cases the reaction was stereoselective and isomers bearing an alpha-carbon atom with an (S)-configuration were hydrolyzed preferentially. Also a lack of stereo selectivity toward the phosphorus atom was observed. Hydrolysis of one enantiomeric mixture, namely mixture of (S-p,R) and (R-p,S) configuration afforded enantiomerically pure ethyl (R-p,S)-hydrox (phenyl)methane(P-phenyl)phosphinate, configuration of which was established by X-ray crystallography. The observed H-1 and P-31 NMR chemical shifts of Mosher esters of ethyl hydroxy(phenyl)methane(P-phenyl)phosphinate were correlated with the configurations of both stereogenic centers of all four stereoisomers. (c) 2006 Elsevier Ltd. All rights reserved.
Different approaches to the synthesis of 1-chloroalkylphosphinates are described. Initially, we tried to extend a reaction described by Kabachnik for the preparation of chloromethylphosphinic acid chlorides [R1(Cl)P(O)CH2Cl] to C-substituted derivatives. We also considered the possibility of synthesizing the title compounds by routes already described for the formation of diethyl 1-chloroalkylphosphonates. Although these methods have allowed us to obtain several of the desired phosphinates, they suffer from limitations that restrict their synthetic applications. Finally, we have developed a more general approach that allows the formation of a wide range of phosphinates. It involves a selective P–C bond formation by reaction of MeMgCl and PhMgCl with phosphonochloridates, which are prepared by P-chlorination of 1-chloroalkylphosphonates.