Vinylnitrene Formation from 3,5-Diphenyl-isoxazole and 3‑Benzoyl-2-phenylazirine
journal contributionposted on 15.11.2013, 00:00 by Disnani W. Gamage, Qian Li, R. A. A. Upul Ranaweera, Sujan K. Sarkar, Geethika K. Weragoda, Patrick L. Carr, Anna D. Gudmundsdottir
Photolysis of 1 in argon-saturated acetonitrile yields 2, whereas in oxygen-saturated acetonitrile small amounts of benzoic acid and benzamide are formed in addition to 2. Similarly, photolysis of 2 in argon-saturated acetonitrile results in 1 and a trace amount of 3, whereas in oxygen-saturated acetonitrile the major product is 1 in addition to the formation of small amounts of benzoic acid and benzamide. Laser flash photolysis of 1 results in an absorption due to triplet vinylnitrene 4 (broad absorption with λmax at 360 nm, τ = 1.8 μs, acetonitrile) that is formed with a rate constant of 1.2 × 107 s–1 and decays with a rate constant of 5.6 × 105 s–1. Laser flash photolysis of 2 in argon-saturated acetonitrile likewise results in the formation of triplet vinylnitrene 4 but also ylide 5 (λmax at 440 nm, τ = 13 μs). The rate constant for forming 4 in argon-saturated acetonitrile is 1.6 × 107 s–1. In oxygen-saturated acetonitrile, vinylnitrene 4 reacts to form the peroxide radical 6 (λmax 360 nm, ∼0.7 μs, acetonitrile) at a rate of 2 × 109 M–1 s–1. Density functional theory calculations were performed to aid in the characterization of vinylnitrene 4 and peroxide 6 and to support the proposed mechanism for the formation of these intermediates.