Stereoselective cyclopropanation of enamides via C-C bond cleavage of cyclopropenes

This work describes a straightforward protocol for the stereoselective synthesis of vinylcyclopropylamides in high E/Z and syn/anti ratios by cyclopropanation of N-tosyl substituted enamides with cyclopropenes in the presence of a rhodium catalyst under very mild reaction conditions. The obtained small rings are further exploited to undergo regioselectively oxidative ring-opening reactions with silver and copper co-catalysts to provide conjugated 1,3-dienyl aldehydes in moderate to good yields. Several vinylcyclopropylamides exhibit good antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo).