- The regioexhaustive functionalization of difluorophenols and trifluorophenols through organometallic intermediates
-
2,4-Difluorophenol, 2,5-difluorophenol, 2,3-difluorophenol, 3,5-difluorophenol, 3,4-difluorophenol, 2,4,5-trifluorophenol and 2,3,4-trifluorophenol were converted into all 18 possible di- or trifluorinated hydroxybenzoic acids (1a-c, 4a-c, 9a-c, 12a,b, 14a-c, 17a,b, 18a,b), all of them new compounds. The phenolic hydrogen atom was replaced by a methoxymethyl or, less frequently, by a triisopropylsilyl group, which exerted an ortho activating or ortho shielding effect, respectively. Sites flanked by two electronegative substituents (fluorine, alkoxy) were deprotonated with particular ease. They had to be silenced by the reversible attachment of a metalation-blocking trimethylsilyl group or of a metalation-deflecting chlorine atom if the metal was to be introduced elsewhere. In all cases but one, the stage was thus set for an intramolecular competition between metalation at an oxygen-adjacent or a fluorine-adjacent site. It proved indeed possible to secure the desired regioflexibility in either way by relying on an appropriate substrate-reagent matching. This demonstrates once more the potential of the organometallic approach to diversity-oriented synthesis.
- Marzi, Elena,Gorecka, Joanna,Schlosser, Manfred
-
p. 1609 - 1618
(2007/10/03)
-
- Regio-selective hydroxysubstitution of fluorobenzoic acid derivatives: Facile synthesis of fluorosalicylic acid derivatives
-
Ortho-substituted fluorine in 2,4-difluorobenzoic acid was found to be regio-selectively replaced to hydroxide by solid sodium hydroxide in 1,3-dimethyl-2-imidazolidinone, to afford 4-fluoro-2-hydroxybenzoic acid in high yield. Several multi-fluoro-substi
- Umezu, Kazuto,Tabuchi, Fumiya,Kimura, Yoshikazu
-
-
- 4-fluorosalicyclic acid derivative and process for production thereof
-
PCT No. PCT/JP97/03761 Sec. 371 Date Jun. 12, 1998 Sec. 102(e) Date Jun. 12, 1998 PCT Filed Oct. 17, 1997 PCT Pub. No. WO98/17620 PCT Pub. Date Apr. 30, 1998The present invention provides a 4-fluorosalicylic acid derivative represented by the following ge
- -
-
-
