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Part-IISynthesis of PyrimidinesTable 31: 4-Amino-2-substituted benzo(b)furo[3,2-d]pyrimidinesR Yield R. Solv. Reference(%)-CH 3 35 B 45-C 6 H 5 48 B 45SC 6 H 5 17 B-M 46CO 2 C 2 H 5 24 B 46CHCl 2 17 B-M 46CH 2 C 6 H 5 21 B-M 46CH 2 CH 2 Cl 18 B-M 46CH 2 C 6 H 4 NO 2 19 B-M 46CH 2 SC 6 H 4 Cl 22 B-P 46B=Benzene, M=Methanol, P=Petroleum etherAngular condensed 4-aminopyrimidines, namely the 4-aminothieno[3,4-d]pyrimidinesand 4-aminoisothiazolo[3,4-d]pyrimidine (Table 32) have also been synthesized throughthe reaction of 3-amino-4-cyanothiophene 12f and 3-amino-4-cyanoisothiazole 12g withnitriles in the presence of dry hydrogen chloride. 31,58R 1CNR 1XS12f, 12gNH 2+ RCNR 2dry HClNH 2NSXN RR 2 IIIeTable 32: 4-Amino-2-substitutedthieno[3,4-d]pyrimidines and 4-aminoisothiazolo-[3,4-d]pyrimidinesR 1 R 2 X R Yield R. Solv. Reference(%)- SCH 3 COOC 2 H 5 C CH 3 64 D-E 31- SCH 3 COOC 2 H 5 C C 6 H 5 51 E 31- SCH 3 COOC 2 H 5 C CO 2 C 2 H 5 60 P-C 58-N OCOOC 2 H 5 C CO 2 C 2 H 5 50 P-C 58- SCH 3 --- N CH 3 45 E-D 31D = Diethylformamide, E = Ethanol, P = Petroleum ether C = ChloroformMolina and co-worker 59 have reacted condensed pyrazole o-aminonitrile 12h withaliphatic nitriles to yield the corresponding 4-amino-2-substitutedpyrazolopyrimidines 18.247