T. Sakamoto*, H. Yamanaka, A. Shiozawa
Jun 25, 1980
Citations
0
Influential Citations
9
Citations
Journal
Chemical & Pharmaceutical Bulletin
Abstract
5-Amino-3-phenylisoxazole-4-carbaldehyde (III) was synthesized by the Vilsmeier reaction of 5-amino-3-phenylisoxazole (I) via N, N-dimethyl-N'-(4-formyl-3-phenylisoxazol-5-yl) formamidine (II). Reaction of III with formamidine and ethyl imidates afforded 3-phenylisoxazolo [5, 4-d] pyrimidine (IVa) and its 6-substituted derivatives (IVb-e), respectively. Condensation of the oxime (V) of III with ethyl orthoformate gave 3-phenylisoxazolo [5, 4-d] pyrimidine 5-oxide, which was readily deoxygenated with PCl3 to give IVa. Treatment of IVa with Grignard reagents gave 4-substituted 4, 5-dihydro derivatives (VIIa, b) which were aromatized with K3Fe (CN)6 to yield 4-substituted isoxazolo [5, 4-d] pyrimidines (VIIIa, b).