4-Amino-6-chloro-2- pyrimidine-5-carbonitrile

The halogen metal exchange reaction between 7-bromo or 7-iodo-3-phenyltriazolopyrimidine 165 and butyllithium in iV,N,N, N -tetra-methylethylenediamine afforded the 7-lithio compound 166, whereas a similar reaction with the 7-chloro derivative 165 (R = H) gave the ring-fission product, 5-amino-l-phenyl-l//-l,2,3-triazole-4-carbonitrile 169 (91 CPB2793). Reaction of 166 with electrophiles such as benzaldehyde and ketones gave 170 and 167 respectively, together with 7,7 -bis[3-phenyl-3//-1,2,3-triazolo[4,5-d]pyrimidine] 168 (Scheme 34). 

Ethyl 4,5-diamino-2-(dimethylamino)thieno[2,3-z/]pyrimidine-6-carboxylate (142) was prepared in 93% yield from 4-amino-6-chloro-2-(di-methylamino)pyrimidine-5-carbonitrile (143) with ethyl 2-mercaptoacetate in refluxing EtOH-THF (5 1) (2000S255). 

In 4-chloro-2-methyl-6-phenylpyrimidine-5-carbonitrile, the reactivity of the chloro substituent allows the introduction of side chains which will cyclize with the adjacent nitrile function. Thus, cyanoacetamide yields 5-amino-2-methyl-7-oxo-7,8-dihydro-4-phenyipyrido[2,3-[Pg.110]

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