Organocatalytic Enantioselective Michael–Acetalization–Henry Reaction Cascade of 2-Hydroxynitrostyrene and 5-Oxohexanal for the Entry to the Hexahydro-6<i>H</i>-benzo[<i>c</i>]chromenones with Four Consecutive Stereogenic Centers and an Approach to Aflatoxin Analogues

Hsieh, Yu-You; Raja, Arun; Hong, Bor‐Cherng; Kotame, Prakash; Chang, Wan-Chen; Lee, Gene‐Hsiang

doi:10.1021/acs.joc.7b02178

Cited by 21 publications

(10 citation statements)

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“…Accounting for the versatile usage of diphenylprolinol TMS ether X Yu‐You Hsieh and co‐workers [87] designed an enantioselective Michael‐acetalization‐Henry reaction between 2‐hydroxynitrostyrene 226 and 5‐oxohexanal 227 to synthesize hexahydro‐6H‐benzo [c] chromenones 228 & 229 containing four contagious stereogenic centers in 2017. The chromenones afforded in satisfactory yields (up to 64 %) with good stereoselectivities (up to 96 : 4 dr, up to 99 % ee).…”

Section: Organocatalytic Enantioselective Michael Addition Reactionsmentioning

confidence: 99%

Enantioselective Organocatalytic Michael Addition Reactions Catalyzed by Proline/Prolinol/Supported Proline based Organocatalysts: An Overview

Pasuparthy

Maiti

2022

ChemistrySelect

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Ever since the discovery of enantioselective organocatalytic Michael addition reactions, it has emerged as a significant path for synthesizing a variety of stereochemical products under mild conditions, also a prominent C−X (X=C, O, N, S) bond formation reaction in organic chemistry. Over time, substantial progress has been accomplished in diversity‐ and target‐ oriented asymmetric Michael addition reactions. This review provides a brief overview of the results, scope, and limitations of several influential strategies involving enantio‐selective Michael addition reactions promoted by mono‐functional proline/prolinol/supported‐proline‐based chiral organocatalysts. Furthermore, we also sincerely believe that the various synthetic strategies documented in this review will pave a pathway to improve the status of Michael addition reactions for synthesizing various drug molecules involving complex intermediates.

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Section: Organocatalytic Enantioselective Michael Addition Reactionsmentioning

confidence: 99%

Enantioselective Organocatalytic Michael Addition Reactions Catalyzed by Proline/Prolinol/Supported Proline based Organocatalysts: An Overview

Pasuparthy

Maiti

2022

ChemistrySelect

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“…The enantioselective Michael-acetalization-Henry reaction of 2-hydroxynitrostyrene and 5-oxohexanal allowed the synthesis of hexahydro-6H-benzo[c]chromenones with four stereogenic centers under Jørgensen-Hayashi catalyst (J-H) followed by oxidation with pyridinium chlorochromate (PCC) (Scheme 6) [15]. It was noted that longer reaction times were required with electron-donating groups on the phenyl ring.…”

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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“…Inspired by the aforementioned background and the continuing efforts in elucidating the organocatalytic domino reactions, 12 we envisioned that the asymmetric synthesis of the chiral spirooxindole motif could be achieved by the reaction of a rationally designed 3-(3-nitroallyl)indolin-2-one ( 1a ) and a nitroolefin bearing an electron-withdrawing moiety in the α-position (Scheme 1). However, the following obstacles impede these domino reactions: (1) the conceivable self-alkylation of nitrooxindole 1 through nitro-Michael additions; 13 (2) efficient activation of the nitroalkene 2 as a Michael acceptor, generating the nitroalkane, and the subsequent alkylation to the nitroalkene moiety on 1 ; and (3) the need to control stereoselectivity in the construction of a sterically hindered spirooxindole with four contiguous stereocenters, including two quaternary centers.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Synthesis of Spirocyclopentane Oxindoles Containing Four Consecutive Stereocenters and Quaternary α-Nitro Esters via Organocatalytic Enantioselective Michael–Michael Cascade Reactions

et al. 2019

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An enantioselective domino Michael–Michael reaction of nitroolefins and 2-nitro-3-arylacrylates has been established, which provided a series of spirocyclopentane oxindoles with four consecutive stereocenters including quaternary α-nitro esters with good yields (up to 73%) and excellent enantioselectivities (up to 97% ee). The reaction was realized and optimized with the aid of a chiral squaramide-amine catalyst. The structures of 11 products were confirmed by single-crystal X-ray diffraction analysis.

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Organocatalytic Enantioselective Michael–Acetalization–Henry Reaction Cascade of 2-Hydroxynitrostyrene and 5-Oxohexanal for the Entry to the Hexahydro-6H-benzo[c]chromenones with Four Consecutive Stereogenic Centers and an Approach to Aflatoxin Analogues

Cited by 21 publications

References 57 publications

Enantioselective Organocatalytic Michael Addition Reactions Catalyzed by Proline/Prolinol/Supported Proline based Organocatalysts: An Overview

Enantioselective Organocatalytic Michael Addition Reactions Catalyzed by Proline/Prolinol/Supported Proline based Organocatalysts: An Overview

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

Asymmetric Synthesis of Spirocyclopentane Oxindoles Containing Four Consecutive Stereocenters and Quaternary α-Nitro Esters via Organocatalytic Enantioselective Michael–Michael Cascade Reactions

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