Aktivierte Chinone: regiospezifische Synthesen von substituierten Dibenzo [ b , d ]pyran‐6‐onen und Benzo [ b ]naphtho [ d ]pyran‐6‐onen

Activated Quinones: Regiospecific Syntheses of Substituted Dibenzo [ b , d ]pyran‐6‐ones and Benzo[ b ]naphtho [ d ]pyran‐6‐ones The reaction of 2‐methoxycarbonyl‐1, 4‐benzoquinone (1) with substituted phenols leads in an acid‐catalyzed, regiospecific way to substituted dibenzo [ b , d ]‐pyran‐6‐ones (compounds 3 and 6 ). The cycloaddition of 1,3‐butadiene to the latter yields compounds 7. Tautomerisation of 7 and oxidation gives the benzo[ b ]‐naphtho[ d ]pyran‐6‐ones 8 and 10 , respectively.