On a practical synthesis of β-hydroxy fatty acid derivatives
摘要:
An efficient synthesis of three homochiral beta-hydroxy fatty acid derivatives, which have been utilized in our total synthesis of lipid A, is reported. The synthesis features Sharpless asymmetric dihydroxylation of an unsaturated ester, regioselective conversion of a diol into acyloxy chlorides, and a reductive removal of the chloro group.
A novel one-pot procedure for the stereoselectivesynthesis of α-hydroxy estersfrom ortho esters was developed. Key steps were multi-heteroatom Cope rearrangements of O-acylated N-hydroxy-l-tert-leucinol-derived oxazoline N-oxides leading to α-acyloxy oxazolines and, after methanolysis, to the target molecules in 67−80% yield and 94−98% ee.