Photorearrangements of 1-methoxy-8-phenylbicyclo[4.2.0]octa-3,7-diene-2,5-dione

✍ Scribed by F.A.L. Anet; Duncan P. Mullis

• Publisher: Elsevier Science
• Year: 1969
• Tongue: French
• Weight: 170 KB
• Volume: 10
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)87796-0

✦ Synopsis

Recently Pappas and Pappas (1) have shown that acetylenes add photochemically to methoxy-p-benzoquinone to give derivatives of bicyclo[4.2.0]octa-3,7-diene-2,5-dione, The exact structure (Ia or Ib) of the phenylacetylene-methoxybenzoquinone adduct I was not determined. We have now found that this adduct can be rearranged (2) photochemically (450watt Hanovia medium-pressure mercury lamp with Pyrex filter) in benzene solution to two structural isomers, II and III. Thus the original adduct must have structure Ia.

Compounds II and III were separated by silica-gel chromatography, with benzene as eluant. They gave correct elementary analyses and their structures follow from the evidence given below. Isomer II was obtained in 55% yield as orange plates, mp 128-129", has hmax