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Markovnikov Wacker‐Tsuji Oxidation of Allyl(hetero)arenes and Application in a One‐Pot Photo‐Metal‐Biocatalytic Approach to Enantioenriched Amines and Alcohols
Author(s) -
AlbarránVelo Jesús,
GotorFernández Vicente,
Lavandera Iván
Publication year - 2021
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202100351
Subject(s) - chemistry , catalysis , enantiopure drug , photocatalysis , combinatorial chemistry , biocatalysis , kinetic resolution , amine gas treating , photochemistry , photoredox catalysis , palladium , wacker process , organic chemistry , reaction mechanism , enantioselective synthesis
The Wacker‐Tsuji aerobic oxidation of various allyl(hetero)arenes under photocatalytic conditions to form the corresponding methyl ketones is presented. By using a palladium complex [PdCl 2 (MeCN) 2 ] and the photosensitizer [Acr‐Mes]ClO 4 in aqueous medium and at room temperature, and by simple irradiation with blue led light, the desired carbonyl compounds were synthesized with high conversions (>80%) and excellent selectivities (>90%). The key process was the transient formation of Pd nanoparticles that can activate oxygen, thus recycling the Pd(II) species necessary in the Wacker oxidative reaction. While light irradiation was strictly mandatory, the addition of the photocatalyst improved the reaction selectivity, due to the formation of the starting allyl(hetero)arene from some of the obtained by‐products, thus entering back in the Wacker‐Tsuji catalytic cycle. Once optimized, the oxidation reaction was combined in a one‐pot two‐step sequential protocol with an enzymatic transformation. Depending on the biocatalyst employed, i. e. an amine transaminase or an alcohol dehydrogenase, the corresponding ( R )‐ and ( S )‐1‐arylpropan‐2‐amines or 1‐arylpropan‐2‐ols, respectively, could be synthesized in most cases with high yields (>70%) and in enantiopure form. Finally, an application of this photo‐metal‐biocatalytic strategy has been demonstrated in order to get access in a straightforward manner to selegiline, an anti‐Parkinson drug.