Reactions of the sodium salts of some heterocyclic β-ketoesters with dimethyl acetylenedicarboxylate

Abstract

The sodium salts of several 1,2,3,4-tetrahydro-4-methoxycarbonyl-1-benzazepin-5-ones were treated with dimethyl acetylenedicarboxylate to give 1,2,3,6-tetrahydro-1-tosyl(and methyl)-4,5,6-trismethoxycarbonyl-1-benzazonin-5-ones. The sodium salt of 3-methoxycarbonylindol-3-one, on similar treatment, gave a red adduct which was converted by silica into a lactone whose structure was elucidated by X-ray crystallography. When the same sequence was applied to 3-methoxycarbonyl-y-butyrolactone, the Michael adduct was obtained in good yield but other N-alkyl and N-aryl β-ketoesters from tetrahydroquinol-4-one, pyrrolidin-2-one, and piperidin-4-one gave intractable mixtures.