Rhodium-Catalyzed Enal Transfer with -Methoxypyridazinium Salts.

Herein, we report a simple method for functionalized enals involving enal-transfer reaction of water-soluble -methoxypyridazinium salts. This open-flask reaction proceeds under mild aqueous basic conditions through [2,3]-sigmatropic rearrangement of propargyl/allyl sulfur-ylides derived from in situ-generated Rh-()-enalcarbene. Various synthetically challenging allene- and allyl-functionalized ()-enals with a γ-C(sp) quaternary center were obtained in good to high yields.