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Biocatalytic Synthesis of Chiral 1,2,3,4-Tetrahydroquinolines
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Yongzheng Chen, Liu Song, Zhongqiang Wang
In 2017, with our efforts to improve the efficiency and synthetic application, we have developed a novel combinational catalyzed asymmetric transfer hydrogenation and sequential enantioselective hydroxylation process with 2-substitute quinolines 8, providing chiral 2-subsituted-tetrahydroquinoline-4-ols 9 in moderate to excellent results (14–17 yield, 77:23–99:1 dr and >99% ee) (Wang et al., 2017). The Rh-catalyzed asymmetric transfer hydrogenation of 8 with (R,R)-Ts-DPEN and (Cp⁄RhCl2)2 in situ as catalyst, and HCO2Na as hydrogen source was an efficient method for chiral 1,2,3,4-tetrahydroquinolines, which afforded the synthesis of the desired product in 98% conversion with 97% ee. However, the intermediates were not isolated but instead, directly mixed with R. equi ZMU-LK19 cells in pH 5.0 using HOAc/NaOAc as buffer system. The one-pot process satisfactorily yielded (R, R)-9a in 47% yield with 99:1 dr and >99:1 ee. The decreased yields with other 2-substituted quinolines as substrates demonstrated steric hindrance effect in agreement with the results of 2-substituted THQs catalyzed by R. equi ZMU-LK19 independently (Scheme 19.7). Asymmetric transfer hydrogenation and sequential enantioselective hydroxylation of 2-substituted THQs.
Name Reactions
Published in Benny K.G. Theng, Clay Mineral Catalysis of Organic Reactions, 2018
Sartori et al. (2001) used a commercially available H+-exchanged bentonite to promote the aza-Diels−Alder cycloaddition of the imine (3), formed by the reaction between aniline (1) and p-chlorobenzaldehyde (2), with cyclopentadiene (4) to yield tetrahydroquinoline (5) according to Scheme 5.9. Zhu et al. (2009) were able to synthesize tetrahydroquinoline skeletons by an aza-DA reaction of methylenecyclopropanes with ethyl (arylimino) acetates, using K10 montmorillonite as the catalyst. Likewise, Akiyama et al. (2002) could obtain 2-substituted 2,3-dihydro-4-pyridones by the aza-DA reaction of Danishefsky’s diene (trans-1-methoxy-3-trimethylsilyloxy-1,3-butadiene) with aldimines, formed in situ from aliphatic aldehydes and p-anisidine. KSF montmorillonite is similarly efficient in catalyzing the three-component aza DA reaction (in acetonitrile) of methylenecyclopropane with arenecarbaldehydes and arylamines to form quinolone derivatives with a spirocyclopropyl ring in 90%–100% isolated yield (Shao and Shi 2003).
A review on synthetic investigation for quinoline- recent green approaches
Published in Green Chemistry Letters and Reviews, 2022
Ashish Patel, Stuti Patel, Meshwa Mehta, Yug Patel, Rushi Patel, Drashti Shah, Darshini Patel, Umang Shah, Mehul Patel, Swayamprakash Patel, Nilay Solanki, Tushar Bambharoliya, Sandip Patel, Afzal Nagani, Harnisha Patel, Jitendra Vaghasiya, Hirak Shah, Bijal Prajapati, Mrudangsinh Rathod, Bhargav Bhimani, Riddhisiddhi Patel, Vashisth Bhavsar, Brijesh Rakholiya, Maitri Patel, Prexa Patel
Ramesh et al. have developed a one-pot multi-component synthetic approach for tetrahydroquinoline by reacting ethyl acetoacetate, dimedone, and ammonium acetate with aromatic aldehydes using silica iodide [SiO2-I] as a catalyst and ethanol as a solvent under reflux for 2–3 h at 80°C to obtain excellent yield of 90% (Scheme 20). This protocol's features include high atom ability and recoverability of the catalyst (58).