Pyrimidine, reaction with organolithiums

Unsubstituted tetrazolyl derivative 458 was also prepared according to the following procedure (91MIP2). A solution of 5-phenyl-2-trityltetrazole in tetrahydrofuran was first treated with 1.7 M ferf-butyllithium in pentane at -25°C, in two parts. After about 30 minutes, an organolithium salt precipitated. Then a 1 M ethereal solution of zinc chloride was added to the mixture, which was then warmed to room temperature. Bis(triphenyl-phosphine)palladium(Il) chloride and 4//-pyrido[l,2-a]pyrimidin-4-one 457 were added to the reaction mixture, and after boiling for 4 hours, the 2-trityl derivative of 458 was obtained in 56% yield. Finally, detritylation with a mixture of methanol and concentrated hydrochloric acid yielded tetrazole derivative 458. 

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