THE SCHMIDT REACTION OF DIALKYL ACYLPHOSPHONATES

The scope of the Schmidt rearrangement of ketones has been extended to dialkyl acylphosphonates (11a-111). Surprisingly, it was found that 1 1a-11d and 11g, in which the acyl moiety was benzoyl alone or benzoyl bearing an electron-attracting or mildly electron-releasing substituen t, yielded an overwhelming portion of products resulting from C-to-N m igration of the aryl group (N-arylcarbamoylphosphonates, 12, and N-ary lformamides, 15). Contrariwise, the arenecarbonylphosphonates, which c arry a powerful electron-releasing p-alkoxy group, yielded products re sulting from phosphonate group migration from C to N or elimination (d ialkyl N-arenecarbonylphosphoramidates, 13, and arenecarbonitriles, 17 , respectively). These counterintuitive results are rationalized by ap plication of the concept of ''degree of electron demand'' to this area of intramolecular rearrangements. The possible existence of an additi onal pathway for the Schmidt rearrangement, involving protonation of t he iminodiazonium ion, is proposed.