NEW WAYS OF GENERATING ORGANOTIN REACTIVE INTERMEDIATES FOR ORGANIC SYSNTHESIS

Article abstract of DOI:10.1016/0040-4020(89)80007-9

Progress in generating and applying two important organotin reactive species for organic synthesis is reported. - Stannyl radicals R3Sn^., at present the most used tools for free radical synthesis of complicated target molecules, are generally obtained from the hydrides R3SnH.In a number of cases, however, this is a drawback because of the high radical scavenging power of the latter.New ways of generating R3Sn^., decoupling them from the presence of R3SnH, are developed and discussed: the spontaneous thermal dissociation of distannanes with bulky substituents, the thermal fragmentation of bistannyl benzpinacols, the ketone sensitized mild photolysis of simple distannanes, and the mild photolysis of benzyltin compounds such as 9-stannyl-9,10-dihydro anthracene.Examples of advantageous applications, also in combinations with adjusted H donors, are given. - Stannyl cations R3Sn(+) are used as superior leaving groups in electrophilic aromatic ipso substitution.Examples for their application under very mild conditions include the considerable broadening of the scope of the Friedel-Crafts acylation, the Vilsmeier formylation, sulfinations, and sulfonations.The directing influence of certain other substituents can be overcome by this ipso substitution.