Synthesis and structures of fluoroalkylated triketides

摘要

The synthesis and structures of fluoroalkylated triketides (3,5-dioxo esters) and 1,3,5-triketones-such as 1,1,1-trifluoroheptane-2,4,6-dione-were studied. The synthesis is based on reactions between 1,3-dicarbonyl dianions and esters. In CDCl _3, the fluoroalkylated triketides exclusively exist in the forms of enol tautomers. In [D _6]DMSO, equilibria between enols and keto hydrates, formed by addition of water to the enols, are observed. In [D _6]DMSO, 1,1,1-trifluoroheptane-2,4,6-dione and 5-chloro-1,1,1- trifluoroheptane-2,4,6-dione exist exclusively in the forms of their cyclic hemiketals. In CDCl _3, tautomeric mixtures of the hemiketals and of three open-chained tautomers are observed (among which the dienol tautomers are predominant).