| Abstract
| - A regiospecific and convergent route the lipophilic antifolate piritrexim (PTX) is described in whicha key step is a Pd(0)-catalyzed cross-coupling reaction between 2-amino-3-cyano-4-methyl-5-bromopyridine and 2,5-dimethoxybenzylzinc chloride to form 2-amino-4-methyl-5-(2,5-dimethoxybenzyl)nicotinonitrile. To complete the synthesis, the amino group is replaced by a more reactivebromine atom via nonaqueous diazotization with tert-butyl nitrite, and the resultant bromo nitrileis cyclized with guanidine.
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