Synthesis of 4‐Aryl‐4,6‐dihydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐diones from Biginelli Compounds |
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| Authors: | Gopal Chandra Patra Sankar Chandra Bhunia Monoj Kumar Roy Sudhir Chandra Pal |
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| Affiliation: | 1. Chemistry Department, Midnapore College, Midnapore, W.?B., India, (phone: +91‐32‐22275847;2. fax: +91‐32‐22275847) |
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| Abstract: | Biginelli compounds 1 were first brominated at Me? C(6) with 2,4,4,6‐tetrabromocyclohex‐2,5‐dien‐1‐one to give Br2CH? C(6) derivatives 2 . The hydrolysis of the 6‐(dibromomethyl) group of 2c to give the 6‐formyl derivative 3c in the presence of an expensive Ag salt followed by reaction with N2H4?H2O yielded tetrahydropyrimido[4,5‐d]pyridazine‐2,5(1H,3H)‐dione ( 4c ; Scheme 1). However, treatment of the 6‐(dibromomethyl) derivatives 2 directly with N2H4?H2O led to the fused heterocycles 4 in better overall yield (Schemes 1 and 2; Table). |
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| Keywords: | Biginelli compounds Cyclohexa‐2,5‐dien‐1‐one, 2,4,4,6‐tetrabromo‐ Pyrimido[4,5‐d]pyridazines |
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