With Urea, Isocyanates, or Their Sulfur Analogs

With Urea, Isocyanates, or Their Sulfur Analogs 

Fusion of an o-aminonitrile with urea at 175°-200°C gives an annelated 4-aminopyrimidin-2-one, e.g., the quinolino[2,3-d]pyrimidine 123 from 2-amino-3-cyanoquinoline.117 The reaction is thought to pass through a ureide of the type 124. Because urea begins to self-condense to the biuret at 

Additional examples using urea include the following 2-amino-l-cyano-naphthalene for benzo[/]quinazolines (see32)169 3-amino-4-cyanopyrazole (see 15) for pyrazolo[3,4-d]pyrimidines (see 16)118,170 a 4-amino-5-cyano-imidazole (see 18) for a purine171 and 2-amino-3-cyanothiophene (see 11) for a thieno[2,3-d]pyrimidine (see 12).172 

Examples using thiourea include 3-amino-4-cyanopyrazole for pyrazolo-[3,4-d]pyrimidines118,168 3-amino-4-cyano-l,2,2-trimethyldihydropyrrole (see 11) for 6,7-dihydropyrrolo[3,4-d]pyrimidines (e.g., 125)168 2-amino-l-cyanonaphthalene for benzo[/]quinazolines169 and 2-amino-l-cyano-cyclopentane for 6,7-dihydrocyclopenta[d]pyrimidines.173 Ammonium 

The organic isocyanates have proved useful for making 3-alkyl- or 3-aryl-4-iminoquinazolin-2-ones. Thus, phenyl isocyanate and 2-amino-benzonitrile give rise to 2-phenylureidobenzonitrile (126) (at 20°C), which 

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