Catalytic asymmetric protonation of fluoro-enolic species: access to optically active 2-fluoro-1-tetralone
作者:Markus A. Baur、Abdelkhalek Riahi、Françoise Hénin、Jacques Muzart
DOI:10.1016/s0957-4166(03)00585-8
日期:2003.9
Three racemic a-fluorinated benzyl beta-ketoesters have been synthesized by electrophilic fluorination with Selectfluor(TM). They were submitted to our well established palladium-mediated cascade reaction (deprotection, decarboxylation and protonation of the resulting enolic species) producing optically active alpha-fluoro ketones. With benzyl 2-fluoro-1-tetralone-2-carboxylate as substrate, (S)-(-)-2-fluoro-1-tetralone with up to 65% enantiomeric excess was obtained using quinine as the chiral base and Pd/C type 807104 from Merck as the heterogeneous catalyst. (C) 2003 Elsevier Ltd. All rights reserved.
Silver-mediated direct trifluoromethoxylation of α-diazo esters via the <sup>−</sup>OCF<sub>3</sub> anion
The reaction cascade consisting of deprotection/decarboxylation/asymmetric protonation of enolic species, starting from open-chain benzyl β-oxo esters, has been studied. When carried out in the presence of catalytic amounts of cinchonine, the reaction gave optically active α-aryl ketones with up to 75% ee. Enantio-enriched (S)-3-phenyl-2-butanone can be converted into 2-phenylpropionic acid without