Triphenyl stannane, reaction with

Radical substitution reactions involving allylic tin derivatives could be accompanied by a photoinduced 1,3-rearrangement54,55. A photostationary mixture of cinnamyl(tri-phenyl)stannane with its regioisomer l-phenylprop-2-enyl(triphenyl)stannane has been shown to form in the photolysis of ( )-cinnamyl(triphenyl)stannane in benzene under aerobic conditions, or in the presence of halogenated organic compounds or radicaltrapping reagents (equation 21). 

The reaction of allylstannanes with aldehydes is conceptually very close to the reaction of allylsilanes with aldehydes (Sakurai reaction). Tlie major advantage of allylstannanes reagents is their high reactivity, a characteristic that has facilitated the development of the catalytic reactions. Allylstannanes are about 10,000 times more reactive than the corresponding allylsilanes, as measured by Mayr (Figure 1). The stannyl group increases the reactivity of the double bond by a factor of 10 -10 compared to H. Tributyl stannane is 10 times more nucleophilic than triphenyl stannane. 

A requirement for an a/m-orientation of the hydridic p-C—H and C—metal bonds as in [10] is indicated by the reaction of threo-3-deuterio-2-(trimethylstannyl)butane with triphenylcarbenium tetrafluoroborate in methylene chloride at 24° which yields a mixture of 3-deuterio-l -butene, /ra v-2-deuterio-2-butene, and undeuteriated c/.v-2-butene as the major product (Hannon and Traylor, 1981). Comparison of the product distributions for the protio- and deuterio-stannanes yields primary and secondary isotope effects of 3.7 and 1.1 respectively. These reactions appear to avoid the complications of adduct formation between the triarylcarbenium salt and the hydride donor, but the preferential formation of the cw-2-butenes is not fully explained. The requirement for the anti-orientation is also shown by the relatively low hydride-donating properties of tris[(triphenylstannyl)methyl-methane (Ducharme et ai, 1984a) which adopts a C3-conformation with the P-C—H gauche to all three C—Sn bonds. In contrast, 1,3,5-triphenyl-2,4,6-trithia-1,3,5-tristannyladamantane, in which anti-orientations with respect to the bridgehead C—H bond are locked, shows high reactivity (Ducharme et al., 1984b). 

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