Trialkyltin hydrides synthesis

The chemistry of R3MH (M = Ge, Sn, Pb) is highlighted firstly by the dominance of trialkyltin hydrides in synthesis, and secondly by the prevalence of free-radical chemistry in the large majority of transformations of synthetic significance reported in the literature. 

Hexaorganodistannanes are used in organic synthesis for bringing about free radical reactions where termination by hydrogen transfer from a trialkyltin hydride must be avoided. Typically, 5-10 mole% of the distannane is used, and the reactions are initiated by irradiation with a sun lamp. Examples are given in equations 18-45 and 18-46.58-59... 

Several functionalized trialkyltin hydrides have been prepared and used in organic synthesis. For example, an optically active organotin hydride with binaphthyl as chiral center underwent hydrostannylation with methyl methacrylate leading to a -stannyl ester diastereoselectivity, however, was not sufficient [234]. Although a bowl-shaped organotin hydride with bulky aromatic substituents was prepared, the structurally novel tin hydride resulted in quite high chemoselectivity. When tris(2,6-diphenylbenzyl)tin hydride (TDTH) was used for competitive reduction of carbonyls under the influence of a Lewis acid it was observed that unsaturated carbonyl compounds such as benzaldehyde and a,/ -enones are highly resistant to TDTH reduction (Scheme 12.131) [235]. 

AIBN is one of the most widely used radical initiators in organic synthesis. It is commercially available as white crystals, whose melting point is 65 °C with a half-life of 10 h in toluene at 65 °C. It is often used with trialkyltin hydrides in synthetic reactions (Scheme 6) [9]. 

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