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Decomposition of Alkene Adducts of Thianthrene Cation Radical in Nitrile Solvents. Formation of Alkyl-2-oxazolines and a New Class of Four-Component Products:  5-[(1-Alkoxyalkylidene)ammonio]alkylthianthrenium Diperchlorates

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journal contribution
posted on 24.12.2004, 00:00 by Henry J. Shine, Bing-Jun Zhao, John N. Marx, Teyeb Ould-Ely, Kenton H. Whitmire
The monoadducts (4ad) of thianthrene cation radical perchlorate (1a) and isobutene, 2-methylbutene, 2-methyl-2-butene, and 2-methylpentene decompose spontaneously in acetonitrile (MeCN) solution, with the formation of thianthrene (Th). Decomposition of 4a (1,2-(5,10-thianthreniumdiyl)-2-methylpropane diperchlorate) and 4a‘, the corresponding dihexafluorophosphate, was studied in depth and extensively with 1H and 13C NMR spectroscopy. Decomposition of 4a was found to involve the solvent itself as well as water in the solvent, remaining from incomplete drying, and gave, apart from Th, successively, the perchlorate salts of 2,4,4-trimethyl-2-oxazoline (6) and 2-amino-2-methylpropyl acetate (7). These salts, 6-HClO4 and 7-HClO4, respectively, were prepared and used in understanding the reactions of 4a as well as the relationships among 6, 7, and 2-(acetylamino)-2-methyl propanol (8) in acidified MeCN solution. Decompositions of 4ad in MeCN and other nitriles (RCN) containing an added alcohol (R‘OH) led to new products, 5-[(1-alkoxyalkylidene)ammonio]alkylthianthrenium diperchlorates (5au). These compounds were identified with 1H and 13C NMR spectroscopy and, in part, with X-ray crystallography and elemental analysis. The mechanisms of formation of 57 are discussed.