Preparation of organostannanes by intermolecular radical substitution reactions

Abstract

A new approach to the synthesis of aromatic stannanes via novel radical substitution reaction of aromatic sulfones is presented. Thus, α-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 β-heterocyclic aromatic sulfones derived from indoline and dibenzofuran. The methodology has some liminations 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 as shown in the successful transformation of 25 to the corresponding stannane 4a.