Preparation of organostannanes by intermolecular radical substitution reactions

A new approach to the synthesis of aromatic stannanes via novel radical substitution reaction of aromatic sulfones is presented. Thus, alpha-heterocyclic aromatic sulphones derived from indole, pyrrole, pyrazole, furans and thiophenes undergo rapid and high yielding ipso-substitution to furnish organostannanes. This methodology has been extended to beta-heterocyclic aromatic sulfones derived from indoline and dibenzofuran, The methodology has some limitations as shown in the lack of reactivity of 3-phenylsulfonyl indole derivative 17 and some phenylthio-substituted heteroaromatic systems 22-24. Phenylsulfinyl substituted indoles can also undergo the desired substitution reaction ss shown in the successful transformation of 25 to the corresponding stannane 4a. Copyright (C) 1996 Elsevier Science Ltd