SYNTHESIS OF 2,4-DIAMINO-THIENO[2,3-D]PYRIMIDINES

Synthesis of 2,4‐Diamino‐thieno[2,3‐d]pyrimidines Condensation of 2‐aminothiophene‐3‐carbonitrile (4) with guanidine or sequential addition of CS2 and NH3 to 4 provides 2,4‐diaminothieno[2,3‐d]pyrimidine (7). This compound yields, after sequential addition of sec‐BuLi and either [3‐(trifluoromethyl)benzene]sulfenyl chloride (8) or the corresponding disulfide 9, followed by acidic work up, 2,4‐diamino‐6‐{[3‐(trifluoromethyl)phenyl]thio}thieno[2,3‐d]pyrimidine (10). In another approach, 2‐amino‐5‐{[3‐(trifluoromethyl)phenyl]thio}thiophene‐3‐carbonitrile (11) obtained from 4 and 8 is transformed to 10 by condensation with guanidine. Corresponding to the second route, 2,4‐diamino‐6‐[(naphth‐2‐yl)thio]thieno‐[2,3‐d]pyrimidine (16) is synthesized. Oxidation of 10 with m‐chloroperbenzoic acid gives 2,4‐diamino‐6‐{[3‐(tri‐fluoromethyl)phenyl]sulfinyl}thieno[2,3‐d]pyrimidine (13). Copyright © 1990 Verlag GmbH & Co. KGaA, Weinheim