| 摘要 |
<p>PURPOSE:To obtain a new steroid derivative useful e.g. as a synthetic intermediate for 24,25-dihydroxycholecalciferol effective as a bone metabolism regulation agent by reducing a 22-carboxylic acid ester of a steroid and treating the reduction product with a Grignard reagent. CONSTITUTION:The objective compound of formula II (R is H or OH-protecting group; Y is group of formula III or formula IV) [e.g. 3beta-(t-butyldimethylsilyloxy) cholesto-5,7,25-trien-24R-ol] is produced by reducing a compound of formula I (R<1> is H or OH-protecting group; R<2> is lower alkyl) [e.g. 3beta-(t- butyldimethyloxy)-24,25,26,27-tetrakisnorcholesto-5,7-diene-23-carboxylic acid methyl ester] with aluminum lithium hydride and reacting the obtained 25,26,27- trisnorcholesto-5,7-diene derivative with a Grignard reagent such as isopropenyl magnesium bromide in dry tetrahydrofuran.</p> |
