title: Photoinduced [4 + 4] cycloadditions of o-quinones with oxazoles.
abstract: [reaction: see text] Photocycloadditions of 9,10-phenanthraquinone (PQ) with oxazoles (1a and 1b) gave [4 + 4] products 2 with the O=C-C=O functionality in PQ and the 2-azadiene moiety in oxazole as 4pi addends. Photoreactions of 1-acetylisatin (IS) with 1a, 1c, and 1d gave [4 + 4] product A, which underwent further [2 + 2] reactions with another (3)IS to furnish 5. These regioselective and diastereoselective [4 + 4] photocycloadditions are rationalized by the intervening of the key conformers for ISC and bond formation of the most stable 1,6-diradical intermediates.
authors.affiliation: Department of Chemistry, Nanjing University, Nanjing 210093, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Hoong-Kun
authors.initials: HK
authors.lastname: Fun
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Xu