131086-94-7

Certain tricyclic polyhydroxylic compounds, and their pharmaceutically-acceptable salts, are inhibitors of tyrosine kinase enzymes, and so are useful for the control of tyrosine kinase dependent diseases (e.g., cancer, atherosclerosis).

A general regiospecific synthesis of dibenzopyran-6-one derivatives 1a,c and 8a-i related to ellagic acid is described (Scheme I, Table I).The sequence involves directed ortho metalation-boronation of benzamides 4 to give the arylboronic acids 5, which, upon palladium-catalyzed cross-coupling with alkoxybromobenzenes 6 leads to the biphenylamides 7.BBr3 demethylation followed by acid-catalyzed cyclization affords pyranone 8.In this manner, the naturally occurring dibenzopyranones 1a, autumnariol (1c), and the heterocyclic analogue 13 (Scheme III) were efficiently prepared.