Reactions of haloarenes, haloheteroarenes and dihalobenzenes with triphenylstannyl anions in DMSO and acetonitrile

We studied different haloarenes, haloheteroarenes and dihalobenzenes with P h3Sn- ions in DMSO or acetonitrile (CH3CN) as solvents, in the dark or unde r irradiation to determine whether the halogen metal exchange (HME) reactio n or the S(RN)1 process prevails. With p-chloroanisole the photostimulated reaction is sluggish in DMSO. There is an HME reaction with 2- and 3-chloro thiophene. Bromoarenes (p-bromoanisole, p-dibromobenzene and 1-bromonaphtha lene) and p-iodoanisole react with Ph3Sn- ions faster by an HME mechanism t han by the S(RN)1 process. In the photostimulated reaction of 1-chloronapht halene, 2-chloro and 3-chloropyridines with Ph3Sn- ions in DMSO, the substi tution products are obtained in 72, 82 and 93% yields, respectively. With p -dichlorobenzene the di-substitution product is obtained in 90% yield. All these reactions occur by the S(RN)1 mechanism. Yields improve when the reac tions are carried out in DMSO rather than in CH3CN. (C) 1999 Elsevier Scien ce S.A. All rights reserved.