[2+2] Photocycloadditions of Homobenzvalene

✍ Scribed by Christl, Manfred ;Braun, Max

• Book ID: 102902515
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 716 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970613

✦ Synopsis

Abstract

The irradiation of methyl phenylglyoxylate, benzil, benzophenone, and 1,4‐benzoquinone in the presence of homobenzvalene (3) gave products of the Paternò‐Büchi reaction, i.e. the oxetane derivatives 4–8, 13 and 14, which contain a tricyclo[4.1.0.0^2,7^]heptane subunit. A regioselectivity was observed in favour of the compounds with the 8‐oxatetracyclo‐[5.2.0.0^2,4^.0^3,5^]nonane skeleton (4, 5, 7, 13). In the case of benzophenone, the cycloaddition was competing with the isomerisation of 3 to cycloheptatriene. No cycloaddition but only isomerisation proceeded with acetophenone and acetone. The irradiation of 1,4‐naphthoquinone and cyclopent‐2‐en‐1‐one in the presence of 3 afforded the cyclobutane derivatives 15 and 17, respectively.