Stannyllithium reagents

Bromo-2-chloropyrimidine is stannylated in the 5-position (195) (Scheme 42). The reaction of 2,4-dibromopyrimidine with trimethylstan-nylsodium results in regioselective substitution in the 2-position to furnish 4-bromo-2-trimethylstannylpyrimidine (196), whereas reactions with the corresponding stannyllithium reagent failed (94T275). 

N- (a-Alkoxyalkyl)- and. actions with sodium alkoxidei Trialkylstannylmethylam stannyllithium reagents. 

Trialkylstannylmethylamines. Products are obtained from reaction with the stannyllithium reagents. 

Examples of these compounds are given in Table 19-4. The stannylzinc compounds have been used in the presence of a copper or platinum catalyst for preparing vinylstan-nanes from terminal alkynes or from vinyl triflates,20 83> 84 but these reagents seem to have little advantage over the more readily available stannyllithium or stannylmagne-sium compounds. 

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