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 β-(methylthio)-α,β-unsaturated ketones, 1-sulfonyl-1,2,3-triazoles can be converted into functionalized β-amino-α,β-unsaturated ketones via formation of α-imino rhodium carbene/sulfur ylide and subsequent rearrangement. The products decompose to useful 2-methylthiopyrrole derivatives conveniently in high yield.