The mechanism of the chlorination of I (R = Cl, Br, R1 = CO2Et; R = CO2Et, R1 = Cl, Br) in CH2Cl2 or HCCl3 soln. at low temps. and in the dark was studied with regard to the nature of the reagent and to the fate of the attacking as well as the substituent halogen in the reaction products. The results suggest that the overall process consists of two main steps, i.e., the electrophilic nuclear attack and the subsequent rearrangement of the halogen of the side chain. Halogen migration from nucleus to side chain may occur from either the adjacent β or the vinylogous α' position.
Electrophilic heteroaromatic substitutions. 2. Mechanism of the side-chain halogenation of polysubstituted α-methylpyrroles with molecular chlorine / Angelini, Giancarlo; G., Illuminati; A., Monaci; Sleiter, Giancarlo; Speranza, Maurizio. - In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY. - ISSN 0002-7863. - STAMPA. - 102:(1980), pp. 1377-1382.