Synthesis of 1, 3-Dioxin-4-ones and Their Use in Synthesis.XVI. : 4-Oxo-1, 3-dioxin-5-carboxylic Acids and Related Compounds : Versatile Synthetic Intermediates for the Synthesis of 6-Unsubstituted Six-Membered Heterocyclic Compunds

Abstract

A novel method for the synthesis of so far unknown 1, 3-dioxin-4-ones having a carboxyl group at the 5-position is described. Reaction of formyl Meldrum's acid and an alcohol in an aprotic solvent at 50-60°C gave the corresponding half esters of formylmalonic acid. Treatment of the latter with appropriate ketones in acetic anhydride containing a catalytic amount of p-toluenesulfonic acid gave the desired dioxinone-5-carboxylates.Successful conversion of these 1, 3-dioxin-4-ones either to 1, 3-oxazine-2, 4-dione or uracil derivatives having an alkoxycarbonyl group at the 5-position demonstated that these dioxinones can serve as chemical equivalents for alkoxycarbonylformylketenes.The fact that 5-benzyloxycarbonyl-1, 3-dioxin-4-one can readily be transformed to the so far unknown 5-aminodioxinone derivative indicates further the importance of the dioxinone having a carboxyl group at the 5-position as a new building block for heterocyclic compounds.