Wolff cyclic carbenes

Thermolysis of N,N-dialkyldiazoacetamides in matrices results in formation of ketenes by Wolff rearrangement, as well as competitive formation of C—H insertion products, with ketenes favored for cyclic precursors. Matrix photolysis in argon of 65 forms an unobserved carbene, which leads mainly to the P-lactam 66 and small amounts of the ketene 67 as identified by IR spectroscopy (Eqn (4.34)). Photolysis of 65 in a CO matrix gives capture of the carbene by CO forming ketene rotational isomers syn-68 and anti-68, similarly identified by IR spectroscopy (Eqn (4.35)), while N,N-dimethyl and N,N-diethyl diazoamides form insertion products. ... 

---