and (24S)-samples that were synthesized in routes involving the orthoesterClaisenrearrangement of Δ23-22-allylic alcohols. This is the first synthetic study where the Claisenrearrangement is used to introduce a C-24 quaternary center in a stereospecific manner with acceptable yield. X-ray analysis of 1 confirmed these stereochemical assignments.
Minor and trace sterols in marine invertebrates 40. Structure and synthesis of axinyssasterol, 25-methylfucosterol and 24-ethyl-24-methylcholesterol -- novel sponge sterols with highly branched side chains
作者:Xian Li、Carl Djerassi
DOI:10.1016/s0040-4039(00)81493-8
日期:1983.1
The isolation, structure determination and synthesis of three novel sterols with unusual side chains is reported. A consistent scheme is proposed which accounts for the biosynthesis of all major and minorsterols in this sponge.