Asymmetric synthesis of polysubstituted chiral chromans <i>via</i> an organocatalytic oxa-Michael-nitro-Michael domino reaction

Tang, Cheng-Ke; Feng, Kai-Xiang; Xia, Ai‐Bao; Li, Chen; Zheng, Yayun; Xu, Zhi‐Kang; D, Xu

doi:10.1039/c7ra13525d

Cited by 15 publications

(14 citation statements)

References 57 publications

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“…In general, the reactions occurred with good to excellent stereoselectivity, except for 2-naphthyl-derived nitroolefin 2e which led to the addition–cyclization product 3ae in good enantioselectivity but moderate diastereoselection (entries 12 and 13 in Table 2). It is noteworthy that, contrary to that previously described, 24 the reactions of nitrostyrenes with electron-withdrawing groups occur with better diastereoselection than those with electron-donating substituents (compare entries 3, 4, 6, 7 vs 10, 11). Additionally, the data show that sq- 4 was the best catalyst because it provided higher yields and better stereoselection than sq- 6 (compare entries 3, 6, 10, and 12 vs 4, 7, 11, and 13 in Table 2).…”

Section: Resultscontrasting

confidence: 91%

“…[α] D 23 +71.6 ( c 1.0, CH 2 Cl 2 ) [lit. 24 [α] D 22 +98.2 ( c 1.0, CH 2 Cl 2 , 92% ee, >20:1 dr)]. 1 H NMR (500 MHz, (CD 3 ) 2 CO): δ 4.26 (m, 1H), 4.78 (dd, J 1 = 13.5 Hz, J 2 = 10.4 Hz, 1H), 4.91 (m, 1H), 5.20 (m, 1H), 5.32 (d, J = 2.3 Hz, 1H), 7.08 (m, 1H), 7.11 (m, 1H), 7.28 (m, 1H), 7.31–7.37 (m, 3H), 7.42 (m, 2H).…”

Section: Methodsmentioning

confidence: 99%

“…[α] D 23 +115.1 ( c 1.0, CH 2 Cl 2 ) [lit. 24 [α] D 22 +125.0 ( c 0.1, CH 2 Cl 2 , >99% ee, >20:1 dr)]. 1 H NMR (500 MHz, (CD 3 ) 2 CO): δ 4.51 (dd, J 1 = 10.2 Hz, J 2 = 3.8 Hz, 1H), 5.22 (dd, J 1 = 15.6 Hz, J 2 = 3.8 Hz, 1H), 5.39 (dd, J 1 = 15.6 Hz, J 2 = 10.1 Hz, 1H), 5.79 (dd, J 1 = 2.4 Hz, J 2 = 1.0 Hz, 1H), 5.94 (d, J = 2.3 Hz, 1H), 7.13 (m, 2H), 7.35 (m, 1H), 7.56 (m, 2H), 7.60–7.62 (m, H), 7.71 (m, H), 7.94–7.99 (m, 3H), 8.13 (m, 1H).…”

Section: Methodsmentioning

confidence: 99%

“…The diastereoselective synthesis of dinitro-trisubstituted benzopyrans by cascade oxa-Michael–nitro-Michael reaction of ortho -hydroxynitrostyrene and nitroalkenes was described fifteen years ago, 23 but only very recently, the enantioselective version of that process has been developed 24 by using thioureas and squaramides as catalysts in homogeneous conditions.…”

Section: Introductionmentioning

confidence: 99%

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Diastereo- and Enantioselective Syntheses of Trisubstituted Benzopyrans by Cascade Reactions Catalyzed by Monomeric and Polymeric Recoverable Bifunctional Thioureas and Squaramides

et al. 2018

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4-Vinylphenyl-substituted squaramides have been tested as organocatalysts for the diastereo- and enantioselective synthesis of trisubstituted benzopyrans via an oxa-Michael intramolecular nitro-Michael cascade reaction. Both the enantio- and diastereoselection were good to moderate, depending on the nature of the chiral scaffold in the catalyst. The diastereoselection is better for the most active catalyst because the final products epimerize at C-3 along the time. Supported squaramide sq- 9 prepared by copolymerization of sq- 4 with styrene and divinylbenzene is also effective in promoting the cascade reaction, and it is recoverable and reusable for five cycles maintaining the activity.

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Section: Resultscontrasting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Diastereo- and Enantioselective Syntheses of Trisubstituted Benzopyrans by Cascade Reactions Catalyzed by Monomeric and Polymeric Recoverable Bifunctional Thioureas and Squaramides

et al. 2018

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“…However, how the stereochemistry was obtained was not reported in either the text or the Supplementary Material; perhaps this was done by comparison of data with previous works. ( Xia, Xu and co-workers performed an enantioselective, organocatalytic oxa-Michael-nitro-Michael reaction, but in this case, too, 2-hydroxynitrostyrenes reacted only with β-nitroolefins different from themselves [10]. The reaction afforded chiral chromane derivatives bearing three contiguous stereogenic centers (Scheme 3).…”

Section: Cyclization Of Ortho-hydroxystyrene Derivativesmentioning

confidence: 99%

Recent Advances in Organocatalyzed Asymmetric Synthesis of Benzopyran and Benzodihydropyran (Chromane) Nuclei

Dalpozzo

Mancuso

2019

Symmetry

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Benzopyran and benzodihydropyran (chromane) nuclei are the core structure of many natural products, in particular flavonoids. Many compounds possessing this structure are nutraceuticals, pharmaceutical nutrients. Therefore, benzopyran and chromane scaffolds are important building blocks in organic synthesis and many efforts have been made to set up efficient methods for their synthesis. In particular, asymmetric methods are of great importance, being natural products, and generally chiral substances. This review aims to cover literature in the range 2017-first half of 2019.It should be noted that the oxa-Michael-Henry reaction between two molecules of nitrostyrene was not observed. Symmetry 2020, 12, x FOR PEER REVIEW 4 of 33 Scheme 2. Heterogeneous enantioselective synthesis of chromanes.Xia, Xu and co-workers performed an enantioselective, organocatalytic oxa-Michael-nitro-Michael reaction, but in this case, too, 2-hydroxynitrostyrenes reacted only with β-nitroolefins different from themselves [10]. The reaction afforded chiral chromane derivatives bearing three contiguous stereogenic centers (Scheme 3). The all-S stereochemistry was assigned by X-ray analysis. Subsequently, Andrés, Pedrosa and co-workers extended the reaction to polymer-supported squaramides [11]. Initially, they tested some 4-vinylphenyl-substituted squaramides and found that Squa2 (see Scheme 1, 5 mol%, rt, 12-72 h in dichloromethane) gave the best results (65-88% yields, 63:27 to >99:1 dr, 70-> 99% ee, 13 examples). The absolute configuration was once more (2S,3S,4S) and was established by X-ray analysis. The configuration of the minor isomer was instead established as (2S,3R,4S) by comparison of the 1 H-NMR coupling constants of the two diastereomers. Then Squa2 was co-polymerized with styrene and divinylbenzene and the experiments were repeated (65-86% yields, 58:42 to >99:1 dr, 56-74% ee). The polymer-supported catalyst was also recovered and recycled five times without affecting yields and selectivity. Finally, the enantiomers were obtained from a squaramide derived from (1R,2R)-1,2-cyclohexanediamine instead of Squa2 derived from α-amino acid. The authors attributed the opposite stereochemistry to a different assembly of the ternary complex formed by catalyst, nitroalkene and 2-hydroxynitrostyrene in the two cases. S O HN HO HO OHC Symmetry 2019, 11, 1510 5 of 31 Symmetry 2020, 12, x FOR PEER REVIEW 5 of 33 Scheme 3. Organocatalytic oxa-Michael nitro-Michael domino reaction.Another domino Michael/hemiacetalization (see also Scheme 2, eq 3) was carried out between aliphatic aldehydes and (E)-2-(2-nitrovinyl)phenols under modularly designed organocatalysts (Scheme 4) [12]. Cis-3,4-disubstituted chroman-2-ones were obtained after oxidation of the hemiacetal intermediate or chromanes after dehydroxylation. The reaction was scaled up to 0.5 mmol scale, without significant modification of yield and selectivity. The absolute stereochemistry was determined by the optical rotation of known compounds. Scheme 4. Domino reaction catalyzed by MDO o...

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Nickel(II)‐Catalyzed Diastereo‐ and Enantioselective Michael/ Hemiacetalization Cascade Reaction of α‐Ketoesters with 2‐(2‐Nitrovinyl)phenols

et al. 2019

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A nickel(II)/diamine-catalyzed diastereoand enantioselective Michael/hemiacetalization cascade reaction of α-ketoesters with 2-(2-nitrovinyl) phenols has been established, thus providing a range of structurally diverse polysubstituted chromanes in good yields and excellent stereoselectivities (up to 89% yield, > 20:1 dr, > 99% ee). Moreover, the gram-scale experiment was performed with only 0.5 mol% of catalyst, and tricyclic furanobenzodihydropyran compound was gained by the derivatization of product, which showed the great synthetic potential of this strategy.

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Asymmetric synthesis of polysubstituted chiral chromans via an organocatalytic oxa-Michael-nitro-Michael domino reaction

Abstract: A catalytic asymmetric method for the synthesis of polysubstituted chromans via an oxa-Michael-nitro-Michael domino reaction of 2-hydroxynitrostyrenes with trans-β-nitroolefins has been accomplished.

Cited by 15 publications

References 57 publications

Diastereo- and Enantioselective Syntheses of Trisubstituted Benzopyrans by Cascade Reactions Catalyzed by Monomeric and Polymeric Recoverable Bifunctional Thioureas and Squaramides

Diastereo- and Enantioselective Syntheses of Trisubstituted Benzopyrans by Cascade Reactions Catalyzed by Monomeric and Polymeric Recoverable Bifunctional Thioureas and Squaramides

Recent Advances in Organocatalyzed Asymmetric Synthesis of Benzopyran and Benzodihydropyran (Chromane) Nuclei

Nickel(II)‐Catalyzed Diastereo‐ and Enantioselective Michael/ Hemiacetalization Cascade Reaction of α‐Ketoesters with 2‐(2‐Nitrovinyl)phenols

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