Radical Nucleophilic Substitution of 2-(4-Halophenyl)-2-methyl-1-chloropropane with Enolate Ions of Ketones

PIERINI, A. B.; GALLEGO, M. L.; CRESPO ANDRADA, K. F.

JOURNAL OF ORGANIC CHEMISTRY

American Chemical Society

Año: 2007 vol. 72 p. 3089 - 3092

0022-3263

The photoinitiated reaction of 2-(4-halophenyl)-2-methyl-1-chloropropane 2a,b (halogen= Br, I, respectively) with the anions of pinacolone (3a) and acetophenone (3b) either in DMSO or in liquid ammonia are reported. In DMSO, the main reaction is the SRN1 nucleophilic substitution at the aromatic (Csp2-halogen) center with substitution or reduction at the aliphatic (Csp3-Cl) one. In liquid ammonia, the main reaction is substitution at the aromatic C-halogen site. This difference in product distribution is ascribed to modifications in the rate constant of Csp3-Cl dissociation of the radical anions proposed as intermediates in going from DMSO (rt) to liquid NH3 (-33 °C).