Structure of an unexpected trimer from the reaction of ageratochromene II with aluminum chloride

A new trimer from the reaction of ageratochromene 1] (6,7‐dimethoxy‐2,2‐dimethyl‐1‐benzopyran) with anhydrous aluminum chloride was shown to be 3,4‐dihydro‐6,7‐dimethoxy‐2,2‐dimethyl‐3‐(6′,7′‐dimethoxy‐2′,2′‐dimethyl‐2H‐1‐benzopyran‐4′‐yl)‐4‐(3′,4′‐dihydro‐6′, 7′‐dimethoxy‐2′,2′‐dimethyl‐2H‐1‐benzopyran‐3′‐yl)‐ 2H‐1‐benzopyran. Its structure was confirmed by NMR (¹H, ¹³C, DEPT‐135. COSY, HMBC, HSQC, TOCSY and NOESY), IR, mass spectra and elemental analysis. Copyright © 2002 John Wiley & Sons, Ltd.