193153-75-2Relevant academic research and scientific papers
Formation of 3-Methylene-1,4-cyclohexadienes from α,α,α',α'-Tetraaryl-1,4-benzenedimethanols by the Intramolecular Migration of an Aryl Group
Wada, Masanori,Wei, Wen-Hao,Kirishima, Katsuhiko,Natsume, Satoko,Erabi, Tatsuo
, p. 1413 - 1420 (2007/10/03)
By reactions of diethyl p-phthalate with 2,6-dimethoxyphenyllithium, ΦLi, a tri-substituted compound, p-HOCΦ2C6H4C(O)Φ (1), or tetra-substituted 1,4-benzenedimethanol, p-HOCΦ2C6H4CΦ2OH (2a), were obtained. Compound 1 further reacted with aryllithium, ArLi, to give the 1,4-benzenedimethanols, p-HOCΦ2C6H4CArΦOH (Ar = 4-MeC6H4 2b, 4-MeOC6H4 2c). When 2a was treated with acid in dimethyl sulfoxide, 3-(2,6-dimethoxybenzoyl)-3-(2,6-dimethoxyphenyl)-6-[bis(2,6-dimethoxyphenyl) methylene]-1,4-cyclohexadiene, Φ2C chemical equation presented (4a) was obtained in quantitative yield under a variety of conditions. The reaction is understood to involve an initial formation of carbenium ion, [p-Φ2C+-C6H4CΦ 2OH] (3a), of which the positive charge must be partly shared with the other end of the p-phenylene ring, where one of the neighboring Φ-groups migrates. Reactions in acetone resulted to give 4a or dark-violet crystals of (2′,6′-dimethoxy-4-biphenylyl)bis(2,6-dimethoxyphenyl)carbenium perchlorate, [(4-ΦC6H4)CΦ2]ClO4, depending on the reaction conditions. Reactions in methanol, ethanol, or in hot 2-propanol resulted to give the reduced compound, (4-ΦC6H4)Φ2CH. The 1,4-benzenedimethanols, 2b and 2c, also reacted with perchloric acid in dimethyl sulfoxide to form the 3-methylene-1,4-cyclohexadiene derivatives, Φ2C chemical equation presented (Ar = 4-MeC6H4 4b, 4-MeOC6H4 4c), respectively. Evidence is given by the 1H NMR spectrum, which shows the formation of intermediate carbenium ions 3a - c.
