Synthesis of C21‐C41 fragment of the reported structure of Neaumycin B

Abstract

AbstractStereoselective synthesis of the C21‐C41 fragment 4 of the reported structure of Neaumycin B(1), a 28‐membered macrolide compound with 19‐chiral centers and 6,6‐spiroketal structure, has been described. C21‐C27 fragment 5 was synthesized from the commercially available (S)‐Roche ester 7 using stereoselective allylation and Brown anti‐crotylation as key steps. C28‐C41 fragment 6 was constructed from chiral oxazolidinone auxiliary 13 using Evans syn‐aldol reaction, diastereoselective epoxidation, and (S)‐CBS reduction as key steps. Finally, boron‐mediated acetate aldol reaction of 5 and 6 led to the synthesis of C21‐C41 fragment 4 for the reported structure of Neaumycin B (1).