FACILE PREPARATION OF 2-OXO-2H-1-PYRAN-3-CARBOXYLATES WITH THE ELECTRON-WITHDRAWING GROUP AT THE 5-POSITION

摘要

A simple and facile procedure for the preparation of 2-oxo-2H-1-pyran-3-carboxylate bearing electron-withdrawing groups at the 5-position, such as the alkylcarbonyl and alkoxycarbonyl moieties, was developed. Various 1,3-dicarbonyl compounds were treated with dimethyl (methoxymethylene)malonate in the presence of Cs2CO3 as a base in tetrahydrofuran at room temperature. This method was particularly effective in the syntheses of bicyclic structures, such as 5,6,7,8-tetrahydro-2,5-dioxo-2H-1-benzopyran-3-carboxylates.