Structure elucidation of the photo‐oxidation product of 1‐(9‐phenanthryl)‐4‐phenylbut‐1‐en‐3‐yne

The photo-oxidation product of 1-(9-phenanthryl)-4-phenylbut-1-en-3-yne has been elucidated by chemical and spectroscopic methods (IR, UV, 1H-NMR, 13C-NMR) and independently by X-ray analysis. The structure 6-phenyl-8,9-10,11-dibenzotricyclo[5.4.0.01,6]-4-oxaundeca-2,8,10-trien-5-one has a cyclopropapyrone unit which decomposes on thermolysis or by catalytic hydrogenation.