| Abstract: |
4(3H)‐Pyrimidinone, as well as its 5‐acetoxy and 5‐methoxy derivatives, undergoes selective acetylation at N‐1 when treated with acetic anhydride. In the presence of water, these 1‐acetylpyrimidines undergo spontaneous covalent hydration at C‐2 and cleavage of the 1,2‐bond to give crystalline cis‐3‐acetylamino‐N‐formyl‐acrylamides, generally in good yield. In contrast, the 6‐methyl derivative of 4(3H)‐pyrimidinone forms an equilibrium mixture of acetylated products that undergo the ring opening process to only a very limited extent, the major product (11%) being the 3‐formylamino‐N‐acetylacrylamide derivative formed via N‐3 acetylation and cleavage of the 2,3‐bond. Copyright © 1986 Journal of Heterocyclic Chemistry |
