87995-52-6Relevant articles and documents
Carbanionically Induced -Migrations of ?- and Coordinatively Unsaturated Groups
Hellwinkel, Dieter,Laemmerzahl, Frank,Hofmann, Gunter
, p. 3375 - 3405 (2007/10/02)
According to a general reaction scheme, o-lithioaryl esters 4a,b, amides 13a,b 17b, and amidines 39b of non-enolizable carboxylic acids as well as a corresponding diphenylphosphinic amide 51b react under mild conditions to give the intensely coloured lithium derivatives of o-acylphenoles 6a,b and o-acylarenamines 15a,b, 18a, 41a, 52a, which are finally hydrolyzed to the neutral products 7a,b, 14a,b, 18b, 41b, 52b, respectively.The lithiated precursors of the rearrangement are mostly prepared by halogen/metal exchange reactions.In the case of N,N-di-p-tolylpivalamide 33 such a -rearrangement also could be induced by direct metalation of the educt.With N-methyl-N-phenylpivalamide (29), however, exclusive metalation of the N-methyl group occurs, followed by -migration of the pivaloyl group.Silyl groups, too, can undergo analogous -shifts, as was demonstrated by the rearrangement of the o-lithiated N-(trimethylsilyl)aniline 63b to the o-(trimethylsilyl)anilines 65a,b.When a benzoyl and sulfonyl group can compete for the -shifts, as in the N-tosylated benzamide 47b, only the benzoyl group migrates.However, the migration tendency of the trimethylsilyl group equals that of the benzoyl group as was shown with the N-silylated benzamide 66b.
