A study directed to the asymmetric synthesis of the antineoplastic macrolide acutiphycin under enantioselective acyclic stereoselection based on chiral oxazaborolidinone-promoted asymmetic aldol reactions

A shortening of the reaction path can be realized by using a series of the chiral oxazaborolidinone-promoted aldol reaction with respect to the practi cal synthesis of the (+)-acutiphycin seco acid derivative 5. The linear str ategy is based on the utilization of five aldol reactions with a sequence o f silyl nucleophiles, 7, 8, 35, 10, and 11, in the presence of stoichiometr ic amounts of the promoter, 1 or 2. The construction of the relative config uration between the stereogenic centers is diastereoselectively controlled by the stereochemistry of the promoter used in the enantioselective aldol r eaction, which is nearly independent of that of the substrate (promoter con trol).