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.

Pyridazine N-Oxides as Precursors of Metallocarbenes: Rhodium-Catalyzed Transannulation with Pyrroles.

Pyridazine N-oxides are used for the first time as precursors of metallocarbenes. These nitrogen-rich heterocycles led to the discovery of a novel acceptor and donor-acceptor enalcarbenoids. The synthetic utility of these metallocarbenes was demonstrated in the rhodium-catalyzed denitrogenative transannulation of pyridazine N-oxides with pyrroles to the valuable alkyl, 7-aryl, and 7-styryl indoles.