Pyrrole and Oligopyrrole Synthesis by 1,3-Dipolar Cycloaddition of Azomethine Ylides with Sulfonyl Dipolarophiles

A procedure for the synthesis of functionalized. substituted pyrroles by 1.3-dipolar cycloaddition of azomethine ylides has been developed This protocol is based on the metal-catalyzed cycloaddition of alpha-iminoesters with sulfonyl dipolarophiles, followed by the base-promoted elimination of the sulfonyl groups A wide variety of 2.5-disubstituted and 2.3,5- and 2,4.5-trisubstituted pyrroles have been prepared in satisfactory yields from 1,2-bis(sulfonyl ethylene). beta-sulfonylenones. and beta-sulfonylacrylates This method can be applied in an iterative and straightforward in to the construction of oligopyrroles. from bipyrroles to p pentapyrroles Iterative [n+1] and [n+2] approaches have been devised, the latter involves double 1,3-dipolar cycloaddition from pyrrolyl-based bis(iminoesters)