Multicomponent synthesis of pyrroles from cyclopropanes: a one-pot palladium(0)-catalyzed dehydrocarbonylation/dehydration.

Ring the changes: The cycloaddition of nitrones with 1-carboallyloxy-1-carbomethoxycyclopropanes yields tetrahydro-1,2-oxazines, which in turn undergo a Tsuji dehydrocarbonylation to give dihydro-1,2-oxazines (see scheme; dba = dibenzylideneacetone). Addition of base to this reaction mixture results in clean conversion to pyrroles. The result is a flexible three-component strategy for the synthesis of tetrasubstituted pyrroles.