1972 Volume 45 Issue 7 Pages 2010-2015
The reaction of 2-dimethoxymethyl-3-methoxypropionitrile (1) with acetamidine produces pyrimidopyrimidine (8) via the consecutive process of 1→an intermediate→8. The intermediate was not isolated, but two structures have been proposed for it. We have now succeeded in the isolation of the intermediate and determined it to be 2-methyl-4-amino-5-dimethoxymethyl-5,6-dihydropyrimidine (4). Several key intermediates were also successfully isolated. The novel reaction pathway for the title reaction was concluded to be as follows: the elimination of methanol from 1, followed by the addition of acetamidine affords 3-acetamidinopropionitrile (3), the subsequent quick cyclization of which produces the intermediate, 4; the further elimination of methanol from 4, followed by a replacement reaction with acetamidine, gives an acetamidinomethylene compound (6), which is converted into the final product, 8, via an intermediate (7). Some minor pathways will also be presented.
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