Rhodium(II)‐Catalyzed Decomposition of β,γ‐Unsaturated Diazo Compounds

The Rh II ‐catalyzed decomposition of β,γ‐unsaturated diazo ketones 1 in the presence of MeOH leads via vinylogous Wolff rearrangement to γ,δ‐unsaturated esters 6 ( Schemes 1 and 2 ). A modest asymmetric induction is achieved when the reaction is carried out with chiral tetrakis(pyrrolidinecarboxylato)‐ or tetrakis(oxazolidinonato)dirhodium(II) complexes. Vinyl and phenyl diazoacetates 11 and 20 , respectively, or 1‐diazo‐3‐phenyl‐propan‐2‐one ( 25 ), when subjected to the same reaction conditions, react by OH insertion with MeOH ( Schemes 3–5 ). In the absence of MeOH, phenyl diazoacetates 20 and 25 undergo intramolecular CH insertion to 22 and 26 , respectively. Intramolecular CH insertion occurs with N ‐aryldiazoamides 23 even in the presence of MeOH ( Scheme 5 ).