Synthesis of 1,2,3,4,8,9,10,11-octasubstituted pentacenequinone derivatives and their conversion into substituted pentacenes.

A series of 1,2,3,4,8,9,10,11-octasubstituted pentacenequinone derivatives were prepared by the oxidation of 1,2,3,4,8,9,10,11-octasubstituted pentacenes, which were synthesized by the double homologation method. Oxidation of the pentacenes was carried out with H(5)IO(6) or air and DDQ. These octasubstituted pentacenequinones were converted into 1,2,3,4,6,8,9,10,11,13-decasubstituted or 2,3,6,9,10,13-hexasubstituted pentacene derivatives by the introduction of aryl or alkynyl groups at the carbonyl carbons. The photophysical properties of these new pentacenes have been measured in solution, and the substituent effects are discussed.