Regioselectivity of reductive debromination of substituted pentabromobenzenes with sodium tert-butoxide in DMSO

Abstract

The regioselectivity of reductive debromination of substituted pentabromobenzenes C 6 Br 5 X (X = NH 2 , OMe, Me, H, Cl, F, and NO 2 ) under the action of Bu t ONa in DMSO containing Bu t OH has been studied. The reaction followed the halophilic mechanism via carbanions.

Transformations of 2-alkylidene-4-oxothiazolidine vinyl bromides initiated by bromophilic attack of neutral and anionic nucleophiles

“…9 Perhaloalkanes are rather inert towards nucleophilic displacement reactions, but they can undergo a halophilic attack by various nucleophiles, including phenoxides and alkoxides, 10 thiophenoxides, 10c,10d sec-amines or their salts, 10d,11 phosphorous ylides, 10d,12 triphenylphosphine, 13 enamines and enolates. 10d Halophilic reactions have also been observed in the case of 3-methyl-5-trichloro-methyl-1,2,4-oxadiazole, 14 2-halomethyl-5-nitrofurans, 15 pentafluorohalo-benzenes, 16 substituted pentabromo-benzenes, 17 geminal 5 and vicinal dihalides. 5,18 Protonation of the carbanion 3 to yield 4, i.e., the product of reductive dehalogenation, is often observed in these reactions.…”