Enantioselective Synthesis of 2-Aryl-3-nitro-2H-chromenes Catalyzed by a Bifunctional Thiourea

Zhang, Zhiguo; Jakab, Gergely; Schreiner, Peter R.

doi:10.1055/s-0030-1259956

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Melting points are uncorrected and expressed in °C by MRS-2 Melting point apparatus from Shanghai Apparatus Co., Ltd. 1 H NMR and 13 C NMR spectra were measured in CDCl 3 , MeOD or DMSO-d 6 solution on a Bruker AV-400 or AV-500 spectrometer using TMS as an internal reference. Coupling constant (J) values are given in Hz.…”

Section: Methodsmentioning

confidence: 99%

“…Several reports describe construction of 2-aryl-3-nitro-2H-chromenes in good yields using 1,4-diazabicyclo[2.2.2]octane (DABCO), 7,8 L-pipecolinic acid 9 or C 2 -symmetric pyrrolidine-triazoles 10 as catalysts. The preparation of optically active 2-aryl-3-nitro-2H-chromenes through asymmetric tandem oxaMichael-Henry reactions has also been realized recently, with chiral pyrrolidine derivatives, 11,12 or cinchona alkaloid-derived bifunctional thioureas 13 as catalysts under mild conditions, respectively. Kinetic resolution of racemic 2-aryl-3-nitro-2H-chromenes can also be used to provide their enantioriched forms.…”

Section: Introductionmentioning

confidence: 99%

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Facile access to 2-aryl-3-nitro-2H-chromenes and 2,3,4-trisubstituted chromanes

Wang¹,

Zhang²,

Liu³

2014

Arkivoc

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Using salicylaldehydes and β-nitrostyrenes as starting materials, 2-aryl-3-nitro-2H-chromenes were prepared in good yields (up to 83%) through the combination of 30 mol% of pyrrolidinebenzoic acid catalyzed tandem oxa-Michael-Henry reactions in refluxing ethanol. Additionally, the Michael reactions of 2-aryl-3-nitro-2H-chromenes with acetone were also performed by the same catalytic combination in brine to give 2,3,4-trisubstituted chromanes up to 86% yield with excellent stereoselectivities. The structures of 2-aryl-3-nitro-2H-chromenes and 2,3,4-trisubstituted chromanes are confirmed by X-ray single crystal diffraction analysis. The reductive amination of a suitable 2,3,4-trisubstituted chromane with Zn/HOAc affords a fused tricyclic amine in 92% yield.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Facile access to 2-aryl-3-nitro-2H-chromenes and 2,3,4-trisubstituted chromanes

Wang¹,

Zhang²,

Liu³

2014

Arkivoc

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“…Very recently, Schreiner et al [63] reported a bifunctional thiourea XXXIb catalyzed tandem reaction of salicyl- N -tosylimines 33 with nitroolefins 27 in toluene at room temperature for the synthesis of nitrochromenes 28 , which resulted in poor yield and good enantioselectivities. A broad range of substituted nitrostyrenes was studied for these tandem oxa -Michel-aza-Henry-desulfonamidation processes to afford the corresponding 2-aryl-3-nitro-2 H -chromenes by a kinetically controlled desulfonamidation step (Scheme 17).…”

Section: Reviewmentioning

confidence: 99%

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

Bhanja¹,

Jena²,

Nayak³

et al. 2012

Beilstein J. Org. Chem.

108

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SummaryEnantioselective organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the most significant synthetic methods reported on chiral-amine-catalyzed tandem Michael conjugate addition of heteroatom-centered nucleophiles to α,β-unsaturated compounds followed by cyclization reactions for the enantioselective construction of functionalized chiral chromenes, thiochromenes and 1,2-dihydroquinolines in optically enriched forms found in a myriad of bioactive natural products and synthetic compounds.

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Chiral Bifunctional Thioureas and Squaramides and Their Copolymers as Recoverable Organocatalysts. Stereoselective Synthesis of 2-Substituted 4-Amino-3-nitrobenzopyrans and 3-Functionalized 3,4-Diamino-4H-Chromenes

et al. 2018

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Novel styryl-substituted thioureas and squaramides were obtained in three steps from commercially available 4-hydroxy-3,5-dichloroaniline. These organocatalysts promote cascade reactions in high yields and excellent stereoselection. By using only a 5 mol % loading of catalyst, it is possible to obtain 2,3,4-trisubstituted benzopyrans by reaction of α-amido sulfones derived from salicyladehydes and nitrostyrenes or 2,3,4-trisubstituted 4 H-chromenes by reaction of the same α-amido sulfones with (phenylsulfonyl)acetonitrile in excellent diastereo- and enantioselectivities. Two polymeric thioureas and squaramides were prepared by copolymerization of the best monomeric catalysts with styrene and divinylbenzene and used for the same transformations. These polymers behave also as excellent stereoselective catalysts that can be recovered and reused for five cycles.

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Enantioselective Synthesis of 2-Aryl-3-nitro-2H-chromenes Catalyzed by a Bifunctional Thiourea

Abstract: A bifunctional thiourea-catalyzed tandem approach of oxa-Michael-aza-Henry-desulfonamidation was used to synthesize chiral 2-aryl-3-nitro-2H-chromenes. This method provides direct access to the corresponding products in moderate to good yields and enantioselectivities.

Cited by 5 publications

References 4 publications

Facile access to 2-aryl-3-nitro-2H-chromenes and 2,3,4-trisubstituted chromanes

Facile access to 2-aryl-3-nitro-2H-chromenes and 2,3,4-trisubstituted chromanes

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

Chiral Bifunctional Thioureas and Squaramides and Their Copolymers as Recoverable Organocatalysts. Stereoselective Synthesis of 2-Substituted 4-Amino-3-nitrobenzopyrans and 3-Functionalized 3,4-Diamino-4H-Chromenes

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