Synthesis and Structural Characterization of 1-(-1-Arylpropenon-3-yl)-3,4,6-tri--benzyl-d-glucals and Their Transformation into Pentasubstituted (2,3,4)-Chromanes Pd-Catalyzed Cross Dehydrogenative Coupling Reaction.

We have developed an efficient methodology for the synthesis of (2,3,4)-2-hydroxymethyl-3,4-dihydroxy-6-aryl-7-aroylchromanes in which the chirality at the -2, -3, and -4 positions is being drawn from -glucopyranosyl aldehyde, which in turn can be efficiently synthesized from d-glucose. Thus, the synthesis starts with the transformation of sugar aldehyde into 1-(-1-arylpropenon-3-yl)-3,4,6-tri--benzyl-d-glucals using Claisen-Schmidt type condensation reaction with different acetophenones and then to 1,2-disubstituted glucals Pd(II)-catalyzed cross dehydrogenative coupling reaction, which in turn has been efficiently converted into (2,3,4)-chromanes 6π-electrocyclization and dehydrogenative aromatization.