Methyltrioxorhenium as Catalyst of a Novel Aldehyde Olefination

From aldehydes or cyclic ketones, diazoalkanes, and tertiary phosphanes, olefins may be prepared according to Equation (a) with MTO as catalyst. In particular, diazoacetates and ‐malonates (R², R³H, CO₂,Et, or 2 × CO₂ Me) can be transformed into olefins with aliphatic and aromatic aldehydes (R¹iPr, trans‐PhCHCH, Ph, 4‐NO₂C₆H₄, etc.). Readily accessible starting materials, easy handling, mild reaction conditions, and good yields characterize the new synthesis method. (R′Ph, 3‐C₆H₄SO₃Na, nBu.) (Figure Presented.)