Ammonium ylide versus carbonyl ylide formation in the rhodium(II)-catalyzed decomposition of diazoacetylureas. Generation and X-ray structure of a stable five-membered N-acyl ammonium ylide
作者:C.Oliver Kappe
DOI:10.1016/s0040-4039(97)00618-7
日期:1997.5
The Rh(II)-catalyzed decomposition of diazoacetylurea 5 gives rise to carbenoid intermediate 7 which can either cyclize to ammonium ylide 6 or to the isomeric carbonylylide dipole 8. In the presence of a rhodium catalyst, ammonium ylide 6 rearranges to carbonylylide 8 which undergoes 1,3-dipolar cycloaddition reaction with DMAD to give furan 12.