Use of .BETA.-ketocarboxylic acids for syntheses of 6-substituted 4-hydroxy-2-pyrones and acyclic .BETA.-diketones.

β-Ketocarboxylic acids including β-ketoglutaric acid half-esters were cyclized by treating them with 1, 1'-carbonyl-diimidazole to give 6-substituted 3-acyl-4-hydroxy-2-pyrones in good yields. 5-Aryl-3, 5-dioxo-1-pentanoic acid and monomethyl malonate gave 6-aryl-4-hydroxy-2-pyrone and dimethyl β-ketoglutarate, respectively, on similar treatment. Anibin, one of the Aniba alkaloids, was synthesized from 5-(3-pyridyl)-4-hydroxy-2-pyrone. In addition, it was confirmed that reaction of magnesium β-ketocarboxylate with acylimidazolide gave the corresponding acyclic β-diketone in excellent yield.