Reinvestigation of the reaction between 1,3-diketones and 2-hydroxyarylaldehydes: a short, atom-economical entry to tetrahydroxanthenones

Abstract

A short and facile access to novel functionalized tetrahydroxanthenones via a DABCO-promoted tandem Knoevenagel condensation/hemiketalisation process from easily accessible substrates in a high yield. Tetrahydroxanthenones provide access to the stereo-controlled synthesis of triades or tetrades, which represent privileged structural motifs. Disubstituted tetrahydroxanthenones are generated as a mixture of diastereomers, favoring the formation of selective diastereomers. Unsymmetrical cyclic diketones give mixtures of regio isomers, favoring the formation of sterically less-hindered products.