The Chemistry of 5-Oxodihydroisoxazoles. XXI Amidines and Pyrimidin-4-ones from the Reaction of Isoxazol-5(2H)-ones with Amines

Abstract

While isoxazol-5(2H)-ones substituted with heterocycles at C2 but unsubstituted at C3 react with amines to give either amidines or malonamides, their reaction at low temperatures with lithium dialkylamides is a preparatively useful procedure for obtaining the amidines in most cases. Longer reaction times may lead to formation of pyrimidin-4-ones when ester groups are present at C4 of the isoxazolone.

A short and efficient method for the synthesis of pyrimido[1,2-a]quinolines

“…The reaction of isoxazol-5(2H)-ones, unsubstituted at C-3 atom, with a base is well known [13][14][15][16][17], and the various intermediates (Scheme 2) have been trapped to prepare a large number of heterocyclic systems [18,19]. However, the reaction of 3-substituted compounds with a base is not so well known, and the only reported reactions appear to be those reported by Doleschall [20] who alkylated the anion of ethyl 3-alkyl-2-methyl-5-oxoisoxazole-4-carboxylate in order to obtain γ-alkylated acetoacetates (Scheme 3).…”

Synthesis of new N-Benzoxazole and N-Benzothiazole derivatives of 3-(4-Substituted- phenyl)aminoisoxazol-5(2H)-ones and comparison of their base induced rearrangement

“…[6][7][8][9] However, the reaction of 3-substituted compounds with base is not so well known, and the only reported reactions appear to be that described by Doleschall,10 who alkylated the anion of ethyl 2,3-dimethyl-2,5-dihydro-5-oxo-isoxazole-4-carboxylate, in order to obtain γ-alkylated acetoacetates.…”