Photochemical Transformation of O‐(β‐Arylethyl) Arylimidates into 2, 4‐Diaryl‐5‐iodoxazoles with 1, 3‐Diiodo‐5, 5‐dimethylhydantoin. Issue 22 (20th May 2020)

• Record Type: Journal Article
• Authors: Saito, Aya; Togo, Hideo
• Is Part Of: European journal of organic chemistry. Issue 22(2020)
• Page Start: 3320
• Page End: 3331
• Publication Date: 2020-05-20
• Subjects: Oxazole -- Iminyl Radical -- Imidate -- DIH -- 1, 5‐H shift; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202000383
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : Treatment of O ‐(β‐arylethyl) arylimidates with 1, 3‐diiodo‐5, 5‐dimethylhydantoin (DIH) under irradiation with a tungsten lamp in 1, 2‐dichloroethane gave the corresponding 2, 4‐diaryl‐5‐iodoxazoles and 2, 4‐diaryloxazoles in good to moderate yields, respectively, depending on the aryl group. It was proposed that the reactions proceeded through the formation of N ‐iodoimidates by the reaction of O ‐(β‐arylethyl) arylimidates with DIH, followed by the formation of iminyl radicals via homolytic N–I bond cleavage, the 1, 5‐H shift by the iminyl radicals, the C–I bond formation of the formed carbon‐centered radicals with iodine, the nucleophilic cyclization by the imino groups to form 2, 4‐diaryloxazolines, the oxidation of the formed 2, 4‐diaryloxazolines to 2, 4‐diaryloxazoles, and the iodination of the formed 2, 4‐diaryloxazoles to 2, 4‐diaryl‐5‐iodoxazoles with DIH. Abstract : 2, 4‐Diaryl‐5‐iodoxazoles could be obtained by the treatment of O ‐(β‐arylethyl) arylimidates with 1, 3‐diiodo‐5, 5‐dimethylhydantoin (DIH) under irradiation with a tungsten lamp. This reaction proceeds through multiple stets, i.e., formation of N ‐iodoimidate, iminyl radical, 1, 5‐H shift, 5‐exo‐tet cyclization to oxazoline, oxidation to oxazole, and iodination to 5‐iodoxazole.