Synthesis of β-Amino-α,β-unsaturated Ketone Derivatives via Sequential Rhodium-Catalyzed Sulfur Ylide Formation/Rearrangement

In the presence of a Rh(II) catalyst and beta-(methylthio)-alpha,beta-unsaturated ketones, 1-sulfonyl-1,2,3-triazoles can be converted into functionalized beta-amino-alpha,beta-unsaturated ketones via formation of alpha-imino rhodium carbene/sulfur ylide and subsequent rearrangement. The products decompose to useful 2-methylthiopyrrole derivatives conveniently in high yield.