Pergamon Tetrahedron 54 (I 998) 7849-7856 TETRAHEDRON Telechelic Oligomers by Halogen Atom Transfer Radical Addition Franco Bellesia, Luca Forti,* Elena Gallini, Franco Ghelfi,* Emanuela Libertini and Ugo M. Pagnoni Dipartimentodi Chimica delrUniversit~,Via Campi 183. I--41100.Modem (Italy) Received 26 February 1998; accepted 30 April 1998 Abstract Monodispersed telechelic oligomers have been efficiently prepared by Fe°-FeCI3 promoted halogen atom transfer radical of functional telogens and taxogens. © 1998 ElsevierScienceLtd. All rights reserved. Keywords: Radicals and radical reactions; oligomers; Halogens and compounds: Iron and compounds. Monodispersed telechelic oligomers, especially diols, are widely used as anti-wear and anti- tear additives for metallic surfaces, greasiness grade improvers for hydrocarbons, prepolymers for paintst121, and in the preparation of polyesters and polyurethanes I351. The preparation of telechelic chlorinated oligomers with remarkable propertiesllSl has been deeply investigated by B. Boutevin, who devised two synthetic strategies based on halogen atom transfer radical addition (HATRA)I3sI: 0 the monoaddition of a functional telogen to a fimctional taxogen, and ii) the addition of a functional telogen to both ends of a nonconjugated diene (Scheme 1). Hal / A--, al + //'S A" S A--Hal + ~ ~ . Hal Hal Scheme 1 0040-4020/98/$19.00 © 1998 Elsevier Science Ltd. All rights reserved. PII: S0040-4020(98)00419-0