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Arylation of 2,2-Dimethyl-2H-1-Benzopyrans with Arylpalladium Complexes: A New Synthesis of the 4-Aryl-2,2-Dimethyl-2H-1-Benzopyran (Neoflavene) Ring System
D. V. Tyndall, J. P. Acton and M. J. Meegan
Proceedings of the Royal Irish Academy. Section B: Biological, Geological, and Chemical Science
Vol. 89B (1989), pp. 241-250
Published by: Royal Irish Academy
Stable URL: http://www.jstor.org/stable/20494510
Page Count: 10
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The arylation of 2,2-dimethyl-2H-1-benzopyran with 2-chloromercuriophenols in the presence of lithium chloropalladite affords 4-aryl-2,2-dimethyl-2H-1-benzopyrans. To confirm the position of arylation in this reaction an unambiguous synthesis of a 2,2-dimethyl-3-phenyl-2H-1-benzopyran and a 2,2-dimethyl-4-phenyl-2H-1-benzopyran was carried out. 3-Aryl-2H-1-benzopyran-2-ones were treated with methylmagnesium iodide to give the 3-aryl-2,2-dimethyl-2H-1-benzopyran products, while 6,7-dimethoxy-4-phenyl-2H-1-benzopyran-2-one was reacted with methylmagnesium iodide to afford the 6,7-dimethoxy-2,2-dimethyl-4-phenyl-2H-1-benzopyran. Comparison of the ¹H and ¹³C n.m.r data of these products with those obtained from the Heck arylation reaction confirmed that arylation of 2,2-dimethyl-2H-1-benzopyran had occurred at C-4 This reaction offers a new synthetic route to the neoflavene ring system.
Proceedings of the Royal Irish Academy. Section B: Biological, Geological, and Chemical Science © 1989 Royal Irish Academy