In the presence of a catalytic amount of bis(3-methyl-2,4-pentanedionato)nickel(II) (Ni(mac)2), various glycidyl esters are converted into the corresponding glycerol monoester derivatives with molecular oxygen in good to high yields.
A novel 1,2-diol-protecting group, p-silyloxybenzylidene group, has been developed. In addition to the stepwise deprotection conditions including desilylation and the subsequent acidic hydrolysis of the p-hydroxybenzylidene group in AcOH–THF–H2O, we have established the one-pot deprotection under basic conditions [K2CO3 (5 equiv), NH2OH·HCl (5 equiv), and CsF (1 equiv) in MeOH–H2O].
Process for the preparation of cholesterol derivatives and novel
申请人:Hoffmann-La Roche Inc.
公开号:US04568491A1
公开(公告)日:1986-02-04
The invention is concerned with a process for the preparation of 1 hydrogen or hydroxy cholesterol derivatives and intermediates therefor. The compounds of the present invention are useful as intermediates in the preparation of 24,25-dihydroxy and 1.alpha., 24,25-trihydroxycholecalciferol.