Regioselective enzymatic syntheses of C-3 and C-5 carbonate A-ring stereoisomeric precursors of vitamin D
作者:Daniel Oves、Vicente Gotor-Fernández、Susana Fernández、Miguel Ferrero、Vicente Gotor
DOI:10.1016/j.tetasy.2004.07.052
日期:2004.9
The synthesis of selectively modified A-ring precursors for the preparation of 1alpha,25-dihydroxyvitamin D-3 analogues by enzymatic hydrolysis reaction of corresponding dicarbonates has been accomplished. Thus, Candida rugosa lipase (CRL) was found to hydrolyze with high selectivity the C-3 carbonate of stereoisomers 4a,b, and 4d, furnishing C-5 vinyloxycarbonates 5a,b, and 5d. On the other hand, Chromobacterium viscosum lipase exhibit opposite regioselectivity with cis enantiomers 4c and 4d, catalyzing hydrolysis at the C-5 carbonate for 4c and at C-3 position for 4d. In addition, CRL catalyzes the alkoxycarbonylation reaction at C-3 of diol 3d affording the monocarbonate complementary to the one obtained by the enzymatic hydrolysis process. (C) 2004 Elsevier Ltd. All rights reserved.