Single versus double nucleophilic addition of carboxylic acid enolates to anisole tricarbonyl chromium complexes with formation of arylcarboxylic acids and/or tetrahydrobenzofuran-2,5-diones: the size of the substituents on the acid makes the difference

Citation
H. Rudler et al., Single versus double nucleophilic addition of carboxylic acid enolates to anisole tricarbonyl chromium complexes with formation of arylcarboxylic acids and/or tetrahydrobenzofuran-2,5-diones: the size of the substituents on the acid makes the difference, CR AC S IIC, 3(2), 2000, pp. 113-122
Citations number
28
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry
Journal title
COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE C-CHIMIE
ISSN journal
1387-1609 → ACNP
Volume
3
Issue
2
Year of publication
2000
Pages
113 - 122
Database
ISI
SICI code
1387-1609(200002)3:2<113:SVDNAO>2.0.ZU;2-C
Abstract
Potassium enolates of carboxylic acid trimethylsilyl esters, obtained upon interaction of bis(trimethylsilyl)ketene acetals with t-BuOK, react with an isole tricarbonyl chromium to give, directly upon iodine promoted oxidative demetalation, a mixture of the expected carboxylic acids and of bicyclic l actones resulting. on a formal point of view, from a double nucleophilic ad dition of the dianions of the carboxylic acids to the arene complexes follo w ed by hydrolysis of labile dienol ethers. The course of the reaction was highly dependent on the nature of the starting carboxylic acid: enolates re sulting from sterically crowded carboxylic acids led in preference to the l actones, whereas those originating from non-hindered acids gave mostly aryl carboxylic acids. The structures of two of these lactones have been establi shed by X-ray diffraction studies. An intermediate dienol ether originating from the 1,2 addition of t-butyl acetic acid dianion to a double bond of a nisole could be isolated and fully characterized by NMR spectroscopy. (C) 2 000 Academie des sciences / Editions scientifiques et medicales Elsevier SA S.