作者:Leiv Sydnes、Ingebjørg Nes
DOI:10.1055/s-0034-1378898
日期:——
When treated with hydrazine, guanidine, and hydroxylamine, 1,1-diethoxy-5-hydroxyalk-3-yn-2-ones undergo Michael addition and give the corresponding beta, beta-disubstituted alpha, beta-unsaturated olefinic ketones, which are unstable and undergo secondary reactions to form heterocyclic compounds. Hydrazine affords 3,5-disubstituted pyrazoles and hydroxylamine 5-hydroxy-4,5-dihydroisoxazoles in very good yields. Guanidine, however, furnishes complex reaction mixtures, which include the corresponding 2-aminopyrimidines. These results show that cyclization involves attack of the ketone moiety by the bisnucleophile reactive terminal group and not the hydroxyl group present in the starting material.