ACTIVATED QUINONES - REGIOSPECIFIC SYNTHESES OF SUBSTITUTED DIBENZO[B,D]PYRAN-6-ONES AND BENZO[B]NAPHTHO[D]PYRAN-6-ONES

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. Copyright © 1979 Verlag GmbH & Co. KGaA, Weinheim