5-Aminothieno pyrimidine 3// diones

Approach G involves the successive formation of the N(3)-C(4) and C(2)-N(3) bonds of the pyrimidine ring during cascade heterocyclization. Such transformations can be exemplified by condensation of substituted 2-alkoxycarbonyl-3-(R2-car-bonyl)aminothieno[2,3-6]pyridines 95 with primary amines or hydrazine giving rise to fused pyrimidin-4(3A)-ones 96 (1993PH26, 1997KGS847). In the case of R4 = EtO, the reaction gives pyrimidine-2,4-dione derivatives 97 as the final products (1993PH95). 

Several 5-aminothieno[3,4-d]pyrimidine-2,4-diones 358 showed phosphodiesterase inhibitory activity superior to that of theophylline (90MI9 91MI3). 

Cyclization of 5-cyano-6-methylpyrimidine-2,4(l//,3H)-diones 136 with elemental sulfur generated the corresponding 5-aminothieno[3,4-d]-pyrimidine-2,4(l//,3//)-diones 137 (90MI1 91MI2). Similarly, cyclization of 5-cyanopyrimidine-4(3H)-thiones 138 with sulfur afforded the 5-amino-4-thioxo derivative 139 (90LA1215). 

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See also in sourсe #XX -- [ , ]

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