Abstract
Abstract:
For the description of the stereoselectivity of (bio)catalytic asymmetric reactions which may proceed via different regio- or stereo-isomeric pathways (e.g. catalysed by epoxide hydrolases, dehalogenases, sulfatases or glycosidases), a parameter ‘RI’ (Retention–Inversion ratio) was introduced in analogy to the Enantiomeric Ratio (E), which describes enantioselectivity. A computer program was developed for the treatment of the kinetics of such single-step processes, which offer the potential of deracemization, i.e. a single stereoisomeric product is formed from a racemate in an enantioconvergent fashion. By analysis of experimentally determined progress curves of the enantiomeric excess of substrate and product (e.e.S, e.e.P, respectively) and the conversion (c), relative first-order rate constants ki, the enantioselectivity (E) and the RI ratio (RI) can be determined; in addition, processes can be simulated based on assumed ki values. [Copyright &y& Elsevier]
