Photolysis of 5-Azido-3-Phenylisoxazole at Cryogenic Temperature: Formation and Direct Detection of a Nitrosoalkene
Photolysis of 5-Azido-3-Phenylisoxazole at Cryogenic Temperature: Formation and Direct Detection of a Nitrosoalkene
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DOI：
10.3390/molecules25030543
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发表时间：
2020-01
期刊：
影响因子：
4.6
通讯作者：
Upasana Banerjee;William L. Karney;B. Ault;A. Gudmundsdottir
中科院分区：
文献类型：
--
作者：
Upasana Banerjee;William L. Karney;B. Ault;A. Gudmundsdottir
为了提高有机叠氮化物在有机合成中的通用性，需要更好地了解它们的光化学性质。本文采用红外光谱和紫外-可见吸收光谱对叠氮异恶唑1在低温基质中的光反应性进行了表征。叠氮异恶唑1在13k的氩气和77k的2-甲基四氢呋喃（mTHF）中辐照（λ = 254 nm）得到亚硝基烯烃3。利用密度泛函理论（DFT）和完全活性空间自洽场（CASSCF）计算来帮助表征亚硝基烯烃3，并支持所提出的形成机制。亚硝基烯烃3很可能是由叠氮异恶唑1的单线态激发态通过协同机制形成的，或者是由中间的单线态亚硝基裂解形成的，而中间的单线态亚硝基没有经过有效的系统间交叉形成其三重态构型。
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.