Enantioselective Synthesis of (+)-O-Trimethylsappanone B and (+)-O-Trimethylbrazilin

Abstract

The homoisoflavanoid (+)-O-trimethylbrazilin (1b) was prepared in 70% yield and 92% ee by acid-catalyzed rearrangement of O-trimethylsappanol (8) prepared by reduction of (R)-(−)-O-trimethylsappanone B (2b). The key step in the synthesis of (R)-(−)-2b is the reagent-controlled highly enantioselective hydroxylation (94%) of the sodium enolate of (±)-4-chromanone (3b) with the (+)-8,8-dichlorocamphorsulfonvl oxaziridine 7b. © 1993, American Chemical Society. All rights reserved.