Asymmetric trans-dihydroxylation of cyclic olefins by enzymatic or chemo-enzymatic sequential epoxidation and hydrolysis in one-pot

Abstract

Novel and efficient one-pot enzymatic and chemo-enzymatic synthetic methods are developed for the asymmetric trans-dihydroxylations of cyclic olefins 1a and 1bvia sequential epoxidation and hydrolysis. The Novozym 435 ®-mediated epoxidation of cyclohexene 1a and subsequent hydrolysis of the intermediate cyclohexene oxide 2a with resting cells of Sphingomonas sp. HXN-200 in one-pot gave (1R,2R)-cyclohexane diol 3a in 84% ee and 95% conversion. trans-Dihydroxylation of N-benzyloxycarbonyl 3-pyrroline 1b with the same enzymatic system gave the corresponding (3R,4R)-N- benzyloxycarbonyl-3,4-dihydroxy-pyrrolidine 3b in 93% ee and 94% conversion. In the one-pot chemo-enzymatic system, epoxidation of N-benzyloxycarbonyl 3-pyrroline 1b by m-CPBA and subsequent hydrolysis of epoxide intermediate 2b with resting cells of Sphingomonas sp. HXN-200 gave the trans-diol (3R,4R)-3b in 92% ee and 94-97% conversion. While the trans-dihydroxylation of cyclohexene 1a to (1R,2R)-cyclohexane diol 3a is reported for the first time, the trans-dihydroxylation of N-benzyloxycarbonyl 3-pyrroline 1b to (3R,4R)-3b with such an enzymatic or chemo-enzymatic system afforded a much higher product concentration than the same reaction with the system using a microorganism containing the two necessary enzymes. The developed one-pot enzymatic and chemo-enzymatic systems for the asymmetric trans-dihydroxylation of olefins are new, easy to prepare, adjust and operate, are high yielding, complementary to Sharpless asymmetric dihydroxylation and particularly useful for the asymmetric synthesis of cyclic trans-diols. © 2011 The Royal Society of Chemistry.