Banerjee U, Karney WL, Ault BS, Gudmundsdottir AD. Photolysis of 5-Azido-3-Phenylisoxazole at Cryogenic Temperature: Formation and Direct Detection of a Nitrosoalkene.
Molecules 2020;
25:molecules25030543. [PMID:
32012736 PMCID:
PMC7037410 DOI:
10.3390/molecules25030543]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/24/2020] [Accepted: 01/24/2020] [Indexed: 01/15/2023] Open
Abstract
To enhance the versatility of organic azides in organic synthesis, a better understanding of their photochemistry is required. Herein, the photoreactivity of azidoisoxazole 1 was characterized in cryogenic matrices with IR and UV-Vis absorption spectroscopy. The irradiation (λ = 254 nm) of azidoisoxazole 1 in an argon matrix at 13 K and in glassy 2-methyltetrahydrofuran (mTHF) at 77 K yielded nitrosoalkene 3. Density functional theory (DFT) and complete active space self-consistent field (CASSCF) calculations were used to aid the characterization of nitrosoalkene 3 and to support the proposed mechanism for its formation. It is likely that nitrosoalkene 3 is formed from the singlet excited state of azidoisoxazole 1 via a concerted mechanism or from cleavage of an intermediate singlet nitrene that does not undergo efficient intersystem crossing to its triplet configuration.
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