Catalytic asymmetric protonation of fluoro-enolic species: access to optically active 2-fluoro-1-tetralone

Screening of chiral catalysts for enantioselective electrophilic fluorination of β-ketoesters

“…Fluoro-1-oxo-1,2,3,4-tetrahydro-naphthalene-2-carboxylic acid benzyl ester NMR data are in agreement with literature values [16]. The ee value of the product was determined by chiral HPLC analysis using the condition reported previously [11].…”

Enantioselective Decarboxylation of β‐Keto Esters with Pd/Amino Alcohol Systems: Successive Metal Catalysis and Organocatalysis

“…The catalyst system allows the efficient synthesis of linear and cyclic ketones [26,28,29,31] such as indanones, tetralones and chromanones. [24,25,30] The reaction cascade shown in Scheme 1 represents a typical example including deprotection (debenzylation), decarboxylation and asymmetric protonation as key steps. [25][26][27] The deprotection reaction catalysed by metallic Pd provides an acid or a carboxylate 2, which reacts further by decarboxylation to provide an enol or enolate 3.…”

“…The latter possibility is supported by the frequent observation that the characteristics of the supported Pd have a major influence on the reaction rate and enantioselectivity. [28][29][30] Decarboxylation on metallic Pd occurs even at room temperature, [50] but for preparative purposes the reaction is usually carried out at 100-300 8C. [51,52] In addition, formally the enantioselective protonation is similar to enantioselective hydrogenations over Pd modified by strongly adsorbing chiral compounds, such as cinchona alkaloids.…”

Cinchona‐Mediated Enantioselective Protonations

“…Access to optically active 2-fluoro-1-tetralone 53 was achieved using the same palladium-mediated cascade reaction [30]. The catalytic enantioselective decarboxylative protonation of 2-fluoro benzyl b-keto ester 54 in the presence of 30 mol% of quinine 20 afforded enantioenriched (S)-tetralone 53 in 65% ee (Scheme 7.24).…”