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Preparation of Optically Enriched 3‐Hydroxy‐3,4‐dihydroquinolin‐2(1 H )‐ones by Heterogeneous Catalytic Cascade Reaction over Supported Platinum Catalyst
Author(s) -
Szőllősi György,
Makra Zsolt,
Kovács Lenke,
Fülöp Ferenc,
Bartók Mihály
Publication year - 2013
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.201300121
Subject(s) - chemistry , enantioselective synthesis , catalysis , nitro , cinchona , yield (engineering) , combinatorial chemistry , cascade reaction , cascade , medicinal chemistry , organic chemistry , alkyl , materials science , metallurgy , chromatography
The development of a novel heterogeneous catalytic asymmetric cascade reaction for the synthesis of tetrahydroquinolines from 2‐nitrophenylpyruvates is reported. Optically enriched 3‐hydroxy‐3,4‐dihydroquinolin‐2(1 H )‐ones are prepared by enantioselective hydrogenation of the activated keto group over a Cinchona alkaloid‐modified Pt catalyst, reduction of the nitro group and spontaneous cyclization cascade. Acceleration of the enantioselective hydrogenation of the activated keto group over the catalyst modified by Cinchona alkaloids ensured high tetrahydroquinolinone selectivities. The scope of the reaction was checked using twelve substrates. Both yields and enantioselectivities were significantly influenced by the nature and position of the substituents on the phenyl ring. Substituents adjacent to the nitro group considerably increased the product yield, due to their effect on the nitro group′s reduction rate; however, had only a limited effect on enantioselectivities.