Novel goniofufurone and 7-epi-goniofufurone mimics from an unexpected titanium-mediated displacement process

摘要

Treatment of 7-O-benzoyl-5-0-benzyl derivatives of (+)-goniofufurone or 7-epi-(+)-goniofufurone with titanium(IV) chloride or titanium(IV) bromide gave 7-chloro and 7-bromo-7-deoxy-goniofufurone mimics as the main reaction products along with minor amounts of the corresponding C-7 epimers. An unexpected cyclized product, benzoxepane 8 was isolated in some cases.