Supramolecular carbohydrate scaffold-catalyzed synthesis of tetrahydroquinolines (original) (raw)
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Journal of Combinatorial Chemistry, 2004
With the goal of developing a library synthesis of tetrahydroquinoline-derived natural-product-like small molecules, a practical synthesis of enantiomerically pure tetrahydroquinoline scaffold was achieved. An asymmetric aminohydroxylation reaction was the key step in this strategy. This scaffold was further immobilized onto the solid support for the library generation. The library was obtained from three diversity sites: (i) acylation of the hydroxyl group (R 1 ), (ii) coupling of the Fmoc-protected amino acid to the amino group (R 2 ), and (iii) amidation of the N-terminal amine group (R 3 ).
Organic & Biomolecular Chemistry, 2013
A new green protocol for the efficient synthesis of pharmacologically relevant 4-amidyl-2-methyl-1,2,3,4tetrahydroquinolines (THQs) through the domino type ABB' imino Diels-Alder reaction in acidified water in the presence of sodium dodecyl sulphate (SDS) surfactant was developed for the first time. The influence of the SDS micelles and their different concentrations (5.0, 8.2 and 12.0 mM) on reactivity of the imino Diels-Alder reaction was studied. It was found that the best THQ yields (70-99%) are achieved above the critical micellar concentration (12 mM) using pH 1.0-2.5. This procedure resulted in a general and clean environmentally benign protocol to obtain the privileged diastereospecific cis 2,4-disubstituted THQ molecules of highest biological interest. † Electronic supplementary information (ESI) available: Detailed synthetic procedures and spectral data. See
Advanced Synthesis & Catalysis, 2020
The diastereodivergent synthesis of bridged 1,2,3,4-tetrahydroisoquinoline derivatives has been achieved by using appropriate modularly designed organocatalysts (MDOs) that are self-assembled in situ from amino acids and cinchona alkaloid derivatives. The domino Mannich/aza-Michael/aldol reaction between (E)-2-[2-(3-aryl-3oxoprop-1-en-1-yl)phenyl]acetaldehydes and ethyl or benzyl (E)-2-[(4-methoxyphenyl)imino]acetates catalyzed by MDOs gives two different diastereomers of the desired bridged tetrahydroisoquinolines in good yields and excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to >99% ee). The diastereodivergence was achieved in the aldol reaction step.
Synlett, 2005
The stereoselective preparation of 1,4dihydroquinolines possessing a chiral sulfoxide group at C-3 is reported. These novel biomimetic NADH models (R)-1a-b have been shown to be highly enantioselective in the reduction of methyl benzoylformate, producing (R)-methyl mandelate in up to 95% ee. The corresponding quinolinium salts 4a-b have been recovered in good yields. The regenerated models 1a-b could be reused without any significant erosion of the enantioselectivity.
2020
Here, an efficient and biodegradable catalytic system prepared through a simple procedure is presented by using chitosan (Cs), epichlorohydrin (ECH) and trimesic acid (TMA). The obtained bio-based Cs/ECH-TMA was characterized by using different spectroscopic and analytical methods. The Cs-ECH-TMA biopolymeric materials were used, as a bifunctional heterogeneous and green catalyst, for efficient synthesis of biologically-active scaffolds including polyhydroquinolines (PHQs) and acridinediones through Hantzsch reaction in a one-pot reaction. Both PHQs and acridinediones were synthesized in the presence of heterogeneous Cs/ECH-TMA catalyst from their corresponding substrates in EtOH under reflux conditions in high to quantitative yields. The Cs/ECH-TMA catalyst is recyclable and can be reused at least five times.
2020
Here, an efficient and biodegradable catalytic system prepared through a simple procedure is presented by using chitosan (Cs), epichlorohydrin (ECH) and trimesic acid (TMA). The obtained bio-based Cs/ECH-TMA was characterized by using different spectroscopic and analytical methods. The Cs-ECH-TMA biopolymeric materials were used, as a bifunctional heterogeneous and green catalyst, for efficient synthesis of biologically-active scaffolds including polyhydroquinolines (PHQs) and acridinediones through Hantzsch reaction in a one-pot reaction. Both PHQs and acridinediones were synthesized in the presence of heterogeneous Cs/ECH-TMA catalyst from their corresponding substrates in EtOH under reflux conditions in high to quantitative yields. The Cs/ECH-TMA catalyst is recyclable and can be reused at least five times.
A Practical Synthetic Route to Enantiopure 6-Substituted cis-Decahydroquinolines
Organic Letters, 2011
Starting from 4-substituted cyclohexanones, a practical synthetic route to enantiopure 6-substituted cisdecahydroquinolines has been developed, the key steps being a stereoselective cyclocondensation of an unsaturated δ δ δ δ-keto ester derivative with (R)-phenylglycinol and the stereoselective hydrogenation of the resulting tricyclic oxazoloquinolone lactams. Bicyclic phenylglycinol-derived oxazolopiperidone lactams provide a general solution for the synthesis of enantiopure polysubstituted piperidines bearing virtually any type of substitution pattern, including indolizidines, quinolizidines, hydroisoquinolines, other fused and bridged piperidine derivatives, and more complex piperidine-containing natural products and bioactive compounds. 1 Using related tricyclic oxazoloquinolone lactams as enantiomeric scaffolds, we have recently developed a procedure that allows easy access to enantiopure 5substituted decahydroquinolines. 2 Apart from their † Dedicated to Prof. Francisco Palacios on the occasion of his 60 th birthday.
Journal of Saudi Chemical Society, 2017
A convenient green chemistry method through one pot four component tandem synthesis of hexahydroquinoline via enaminone intermediate using dimedone, ammonium acetate, aryl aldehydes and malononitrile has been described in aqueous media without the use of any external catalyst. The excess of ammonium acetate used acts as a reagent as well as catalyst. The incorporation of water as solvent along with eradication of external catalyst renders the protocol to comply with the green chemistry aspects. Shorter reaction time, high atom economy, easy work up and purification of products by non-chromatographic method are the crucial features of this methodology. The crystal structure of hexahydroquinoline basically shaped by chromatographic free selective reaction was determined by single crystal X-ray diffraction analysis.
2018
Salicylic acid was used as an efficient catalyst for the diastereoselective synthesis of dispirohydroquinoline-bis (Meldrim’s acid) derivatives via a one-pot domino eight-component reaction of arylamines, aromatic aldehydes and Meldrum’s acid in CH3CN at room temperature. The remarkable advantages offered by this method are inexpensive catalyst, good yields, simple and easy work-up procedure. The characterization of products was done by IR, mass, 1H NMR, 13C NMR spectroscopy, and elemental analyses. The stereoselectivity of compounds was confirmed with crystallography and NMR spectroscopy.
Organic Letters, 2009
An efficient synthesis of enantiopure 3,4-disubstituted 1,2,3,4-tetrahydroisoquinolines, by treatment of readily available (2R,1′S)-or (2S,1′S)-2-(1-aminoalkyl)epoxides with H 3 PO 4 ·BF 3 complex, under mild reaction conditions, is reported. Both enantiopure diastereoisomers (3S,4S)and (3S,4R)-3-alkyl-4-hydroxymethyl-1,2,3,4-tetrahydroisoquinolines were available starting from the suitable syn-or anti-aminoepoxide, respectively. A mechanism based on an intramolecular Friedel-Crafts-type reaction has been proposed to explain these results.