Organoleads alkynes

In some cases the synthesis of bromine-substituted organolead compounds from Ph3PbLi and an excess of a,w-dibromoalkanes (95) is successful (see Table III). These bromides form azides with sodium azide, which themselves react with alkynes (118) to give triazoles by 1,3-addition. 

As mentioned above, organolead hydrides are also capable of undergoing polar reactions. That this is true can be observed in the hydroplumbation of alkynes 195), where during the addition of MejPbH to cyanoacetylene in diethyl ether the /3-adducts (cis and trans) are formed almost exclusively, whereas 76% of a-adduct is formed in butyronitrile as solvent, probably by means of an ionic reaction (Table XII.)... 

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