| 摘要 |
<p>.alpha.-Pyrones and a process for their preparation and the use thereof Alkoxymethyleneaconitic acid triesters of formula I (I), wherein R1, R2, R3 and R4 are each independently unsubstituted or substituted aliphatic hydrocarbon radicals, can be obtained by reacting aconitic acid triesters with formates in the presence of TiCl4, a tertiary amine and a complexing solvent. Enol ethers of formula I can be cyclised in the presence of strong anhydrous acids, in a manner which is known per se, to 2-oxo-2H-pyran-4,5-dicarboxylic acid diesters of formula V (V) , The pyrones of formula V are intermediates for the synthesis of organiccompounds and can be used for example as diene components in DielsAlder reactions.</p> |
