Experimental and Theoretical Study of the Reactivity of Primary and Secondary Enaminones toward Diphenylketene. A Comparison of AM1 and HAM/3 Semiempirical Methods

Article abstract of DOI:10.1021/jo00304a030

Diazodiphenylethanone (1) reacts with acyclic enamino ketones 2 and enamino esters 3 to form products of electrophilic attack of diphenylketene at C_α (5) and nitrogen (6 and 7).The relative reactivity of the different enaminones was shown to be consistent with HOMO energies determined by the HAM/3 semiempirical method.However, this approach could not completely explain the reactivity of the cyclic enamino ketones 4, which, by HAM/3, show a high energy second HOMO corresponding to the nonbonded pair of electrons on oxygen.