ORGN 368 |
| The addition of ortho-lithioarenes to benzyne has been studied in various media. After settling upon THF as a suitable reaction solvent, a number of separately generated ortho-lithiointermediates were reacted with THF solutions of chlorobenzene (equation). Mechanistically, 1.0 equiv. of ArLi intermediate generates an equivalent of the benzyne intermediate, which adds, 1:1, to the remaining ArLi equivalent. Biphenyls have been prepared from o-lithioanisole, o-lithiodimethylaniline, o-lithiodimethylbenzylamine, o-lithio-1,2-dimethoxybenzene, 2-lithio-1,3-dimethoxybenzene, 2-lithio-1,4-dimethoxybenzene and 2-lithio-4-chloroanisole. Yields based on the aryllithium intermediates are 25-40%, but are twice that based on the limiting reagent, chlorobenzene. Results of efforts to improve the yields based on the aryllithium reagents by use of a separate benzyne-generating base will be presented. Additionally, efforts toward preservation of the various 2'-lithiobiphenyl intermediates, detected in ClSiMe3 derivatization quenches, will be discussed.
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Bioorganic, Metal-Mediated Reactions, and Molecular Recognition
8:00 PM-10:00 PM, Tuesday, 30 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Organic Chemistry |
