Rhodium(II) acetate‐catalyzed Reaction of 2‐Amino‐4,5‐dihydro‐3‐furancarbonitriles with α‐Diazo‐β‐keto Esters

2-Amino-4,5-dihydro-3-furancarbonitriles (1) react with α-diazo-β-keto esters in the presence of rhodium (II) acetate to give alkyl 2H-pyran-2-carboxylates (2) in good yields. Benzoylation of 2 with benzoyl chloride provided alkyl 3-benzoylimino-2H-pyran-2-carboxylates (4). The formation of 2 could be explained by a mechanism involving an oxonium ylide derived from the rhodium carbenoids and 1.