Portal de Periódicos da CAPES

Electrophilic additions to allenes. VII. The role of steric versus electronic effects in the reactions of areneselenenyl halides with allenes

1980; NRC Research Press; Volume: 58; Issue: 24 Linguagem: Inglês

10.1139/v80-439

1480-3291

Dennis G. Garratt, Pierre L. Beaulieu, Veronique M. Morisset, Mark Ujjainwalla,

Chemical Reaction Mechanisms

The reactions of benzeneselenenyl chloride, bromide, and 2,4,6-trimethylbenzeneselenenyl bromide with alkyl 1,3-disubstituted allenes in methylene chloride solution have been investigated. While kinetic data are in accord with similar rate determining transition states, exhibiting strong steric effects for ail three species, the product distributions show changes in both chemoselectivity and configurational-selectivity in accord with two different types of steric interaction mechanisms during the product determining transition states. A mechanism involving rate limiting formation of alkylideneseleniranium ions and/or alkylideneepiselenuranes, followed by isomerization between the alkylideneseleniranium ions by a path not involving allylic ions, prior to the product determining transition states, is proposed.