Photolysis of 3-phenyl-2-methyl-2H-azirine (1a  ) in dichloromethane yields benzaldehyde (2  ) and 1-chloro-1-phenylpropan-2-one (3  ). Similarly, photolysis of 1a  in bromoform yields 2  and 1-bromo-1-phenylpropan-2-one (4  ). However, photolysis of the isomeric 2-phenyl-3-methyl-2H-azirine   (1b  ) in yields a dimer 2,5-dimethyl-3,6-diphenyl-2,5-dihydropyrazine (8  ). Laser flash photolysis of 1b  in acetonitrile results in a long lived transient absorption with maximum at 335 nm that we assign to ylide formation. In comparison, laser flash photolysis of azirine 1a  resulted in a transient absorption with ?max at ~460nm, which has a lifetime of 12 ms. We will present density functional theory calculations to explain the different reactivity of isomers 1a  and 1b  .

Photolysis of phenylazirine derivatives

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.