摘要:
Rhodium(II)-catalyzed decomposition of vinyldiazomethanes in the presence of 1-methoxy-1-[(trimethylsilyl)oxy]buta-1,3-diene leads to [3 + 4] annulation products by a tandem cyclopropanation/Cope rearrangement sequence. The resulting cycloheptadienes are readily converted to cycloheptatrienones either by hydrolysis with mild acid followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or by treatment with dichloroethoxyoxovanadium. The efficiency of the general strategy was demonstrated through a short synthesis of nezukone.