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James B, Sriyarathne HDM, Banerjee U, Henarath Mohottige WKS, Crabtree B, León A, Hong M, Tariq J, Alhayani T, Abe M, Ault BS, Gudmundsdottir AD. α-Cleavage of 2,2-Diazido-2,3-dihydroinden-1-one in Solution and Cryogenic Matrices. J Org Chem 2024; 89:7125-7137. [PMID: 38717956 DOI: 10.1021/acs.joc.4c00499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
The Norrish type I (α-cleavage) reaction is an excellent photochemical method for radical-pair formation in solution. However, in cryogenic matrices, the starting material typically re-forms before the radical pair diffuses apart. This study focused on N2 extrusion from an azido alkyl radical to prevent radical-pair recombination. Irradiation of 2,2-diazido-2,3-dihydroinden-1-one (1) in methanol mainly yielded methyl 2-cyanomethylbenzoate (2) and 2-cyanomethylbenzoic acid (3) via α-cleavage. Laser flash photolysis of 1 in argon-saturated acetonitrile resulted in α-cleavage to form triplet biradical 31Br1 (λmax ∼ 410 nm, τ ∼ 400 ns). In contrast, upon irradiation in glassy 2-methyltetrahydrofuran matrices, triplet alkylnitrene 31N was directly detected using electron spin resonance (D/hc = 1.5646 cm-1, E/hc = 0.00161 cm-1) and absorption spectroscopy (λmax = 276 and 341 nm). Irradiation of 1 in argon matrices generated 31N, benzoyl azide 4, singlet benzoylnitrene 14N, and isocyanide 5, as revealed by IR spectroscopy. The experimental results supported by density functional theory calculations [B3PW91/6-311++G(d,p)] suggest that irradiation of 1 in matrices results in α-cleavage to form biradical 31Br1, which extrudes N2 to yield 31Br2. Rearrangement of 31Br2 into 31N competes with cleavage of a N3 radical to form radical 1Ra3. The N3/1Ra3 radical pair combines to form 4, which upon irradiation yields 14N and 5.
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Affiliation(s)
- Brandi James
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | | | - Upasana Banerjee
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | | | - Ben Crabtree
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Aliz León
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Miao Hong
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Javeria Tariq
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Taha Alhayani
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, Hiroshima 739-8526, Japan
| | - Bruce S Ault
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
| | - Anna D Gudmundsdottir
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, United States
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Kim HE, Choi JH, Chung WJ. Fluorine-Assisted Rearrangement of Geminal Azidofluorides to Imidoyl Fluorides. J Org Chem 2023. [PMID: 37130141 DOI: 10.1021/acs.joc.3c00183] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Organoazide rearrangement constitutes versatile synthetic strategies but typically requires an extremely strong acid and/or a high reaction temperature. Our group recently discovered the remarkable accelerating effect of the geminal fluorine substituent that enables the facile rearrangement of azides into imidoyl fluorides without the aid of acid under much milder reaction conditions. The role of geminal fluorine was elucidated by both experimental and computational investigations. This new reactivity led to the development of a practical one-step tandem preparative method for potentially useful and bench-stable imidoyl fluorides from a wide range of structurally diverse geminal chlorofluorides. Our additional efforts to expand the reaction scope regarding the migrating group, halogen, and carbonyl function are described, and the synthetic utility of the imidoyl fluoride products was demonstrated in hopes of promoting the use of this under-appreciated functional group in the synthetic organic community.
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Affiliation(s)
- Ha Eun Kim
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Jun-Ho Choi
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Won-Jin Chung
- Department of Chemistry, Gwangju Institute of Science and Technology, 123 Cheomdan-gwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
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Ardiansah B, Tanimoto H, Tomohiro T, Morimoto T, Kakiuchi K. Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides. Chem Commun (Camb) 2021; 57:8738-8741. [PMID: 34374377 DOI: 10.1039/d1cc02770k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
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Affiliation(s)
- Bayu Ardiansah
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
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Thenna Hewa K, Sebastien W, Lemen EM, Karney WL, Abe M, Gudmundsdottir AD. Photolysis of 3-Azido-3-phenyl-3H-isobenzofuran-1-one at Ambient and Cryogenic Temperatures. Photochem Photobiol 2021; 97:1397-1406. [PMID: 34346085 DOI: 10.1111/php.13500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/24/2021] [Accepted: 07/29/2021] [Indexed: 11/27/2022]
Abstract
Although alkyl azides are known to typically form imines under direct irradiation, the product formation mechanism remains ambiguous as some alkyl azides also yield the corresponding triplet alkylnitrenes at cryogenic temperatures. The photoreactivity of 3-azido-3-phenyl-3H-isobenzofuran-1-one (1) was investigated in solution and in cryogenic matrices. Irradiation (λ = 254 nm) of azide 1 in acetonitrile yielded a mixture of imines 2 and 3. Monitoring of the reaction progress using UV-Vis absorption spectroscopy revealed an isosbestic point at 210 nm, indicating that the reaction proceeded cleanly. Similar results were observed for the photoreactivity of azide 1 in a frozen 2-methyltetrahydrofuran (mTHF) matrix. Irradiation of azide 1 in an argon matrix at 6 K resulted in the disappearance of its IR bands with the concurrent appearance of IR bands corresponding to imines 2 and 3. Thus, it was theorized that azide 1 forms imines 2 and 3 via a concerted mechanism from its singlet excited state or through singlet alkylnitrene 1 1N, which does not intersystem cross to its triplet configuration. This proposal was supported by CASPT2 calculations on a model system, which suggested that the energy gap between the singlet and triplet configurations of alkylnitrene 1N is 33 kcal/mol, thus making intersystem crossing inefficient.
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Affiliation(s)
- Kosala Thenna Hewa
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, United States
| | - William Sebastien
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, United States
| | - Elaine M Lemen
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, United States
| | - William L Karney
- Department of Chemistry, University of San Francisco, 2130 Fulton Street, San Francisco, CA, 94117, United States
| | - Manabu Abe
- Department of Chemistry, Graduate School of Science, Hiroshima University, Hiroshima, 739-8526, Japan
| | - Anna D Gudmundsdottir
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, United States
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