The key intermediate α-substituted α-tetralone (8) has been synthesized, either via tandem MICHAEL addition-DIECKMANN condensation reaction between dienolate and methyl crotonate in a low yield or via BARTON'S radical decarboxylation of diester (9) without 4- dimethylaminopyridine in 75% yield, and applied to the synthesis of the substituted 5, 6- dihydrobenzo [a] naphthacenequinone.
[Funk, Raymond L.; Fitzgerald, John F.; Olmstead, Thomas A.; Para, Kim S.; Wos, John A. Journal of the American Chemical Society, 1993 , vol. 115, # 19 p. 8849 - 8850]