Acetylierung von N‐(Trimethylsilyl)keteniminen: N‐Acylketenimine und α‐Cyanketone

Acylation of N‐(Trimethylsfly1)ketenimines: N‐Acylketenimines and α‐Cyano Ketones The acylation reactions of N‐(trimethylsilyl)ketenimines 1 with different acyl halides 4 yields N‐acylketenimines 2 and/or α‐cyano ketones 3, depending on the substitution pattern of compounds 1 and the halogen atom in 4. In some cases, novel adducts of enamide type 5, 6 are isolated. The new N‐acylketenimines 2a, b are stable at room temperature and have been fully characterized; compounds 2c, d, however, were found to dimerize yielding the 1,3,5‐oxadiazines 7. For comparison, the analogous acylation reactions of nitrile anions were also studied. MNDO calculations are used to rationalize the regiochemistry in terms of kinetic and thermodynamic control.