1987 Volume 35 Issue 1 Pages 90-96
The reaction of 2-amino-2-thiazoline (1) with acetylene carboxylates (2) afforded 5-substituted 2, 3-dihydro-7H-thiazolo [3, 2-a] pyrimidin-7-ones (3). 7-Bromomethyl-2, 3-dihydro-5H-thiazolo [3, 2-a] pyrimidin-5-one (10) was obtained by the reaction of 1 with γ-bromoacetoacetyl bromide. Treatment of 10 with N-bromosuccinimide provided the 6-bromo compound (12). The 7-bromomethyl compounds (10 and 12) were converted to 7-morpholinomethyl derivatives by treatment with morpholine. When 3a (unsubstituted-), 3b (5-ethoxycarbonyl-), and 3c (5-hydroxymethyl-) were treated with 5% hydrochloric acid, covalent hydration occurred across the 5, 6-carbon-carbon bond, giving 5-hydroxy-2, 3, 5, 6-tetrahydro-7H-thiazolo [3, 2-a] pyrimidin-7-one derivatives (16a, 16b, and 16c). On the other hand, in the case of 11 (7-methyl-) and 17 (5-phenyl-), the dihydrothiazole ring was cleaved to give 3 (and 1) - (2-mercaptoethyl) -6-methyl (and phenyl) -2, 4 (1H, 3H) -pyrimidinedione (19 and 18).
