反应详情

The starting material 6-bromochroman-3-one (5A) was prepared from 6-bromochroman-4-one in a manner similar to that described in the literature (Synthesis, 1980, 621): 6-bromochroman-4-one was reduced with NaBH4 (1.2 eq, MeOH-DCM, 0° C. to RT, 2 h) and then eliminated with pTsOH (cat., toluene, reflux, 3 h, 90% for 2-steps). The resulting 6-bromochromene was subjected to osmylation (cat. OsO4, 1 eq. NMO, water-acetone-tBuOH, RT, overnight) and subsequent treatment with pTsOH (cat., toluene, reflux, 15 min, 86% for 2-steps) to provide 6-bromochroman-3-one (5A).

1. customthat described in the literature (Synthesis, 1980, 621)