摘要:
The A-ring precursor of 1 alpha,25-dihydroxyvitamin D-3 [(E)-4] has been prepared starting from the (5S)-tert-butyldimethylsiloxy-2-cyclohexenone [(S)-1] via eight steps in 19% overall yield, where a catalytic osmium dihydroxylation which sets the stereochemistry of the hydroxyl group at C-1 and a regioselective protection of the hydroxy group as a TBS-ether are the key steps. (C) 2000 Elsevier Science Ltd. All rights reserved.