Enantioselective Construction of All‐Carbon Quaternary Stereogenic Centers by Using Phosphine Catalysis

Li, Huilin; Lü, Yixin

doi:10.1002/ajoc.201700220

Cited by 104 publications

(32 citation statements)

References 112 publications

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“…Phosphine catalysis has been recognized as a reliable tool for the development of unique transformations of allenoates, allowing for the discovery of novel asymmetric synthetic methodology (Lu et al, 2001;Methot and Roush, 2004;Ye et al, 2008;Cowen and Miller, 2009;Wei andShi, 2010, 2017;Fan and Kwon, 2013;Wang et al, 2014Ló pez and Mascareñ as, 2014;Xie and Huang, 2015;Li and Zhang, 2016a;Li and Lu, 2017;Ni et al, 2018;Guo et al, 2018). Considerable research efforts have been devoted to the development of new methods for the phosphine-catalyzed enantioselective reactions.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective [4+2] Annulation to the Concise Synthesis of Chiral Dihydrocarbazoles

Wang

et al. 2020

iScience

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A highly efficient phosphine-catalyzed enantioselective [4 + 2] annulation of allenoates with 3-nitroindoles or 3-nitrobenzothiophenes has been developed. The protocol represents a unique dearomatizationaromatization process to access functionalized dihydrocarbazoles or dihydrodibenzothiophenes with high optical purity (up to 97% ee) under mild reaction conditions. The synthetic utility of the highly enantioselective [4 + 2] annulation enables a concise synthesis of analgesic agent.

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Section: Introductionmentioning

confidence: 99%

Enantioselective [4+2] Annulation to the Concise Synthesis of Chiral Dihydrocarbazoles

Wang

et al. 2020

iScience

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“…The reaction mechanism could be proposed, as shown in Scheme . The reaction of 1a and PPh 3 generated the corresponding phosphorous ylide I . A following Wittig reaction of I and 2a afforded the corresponding triene II as a E/Z mixture at the α,β‐position .…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Spirocyclohexadieneyl‐2‐Oxindoles by 6π‐Electrocyclization of Trienes Derived from Wittig Reaction of Morita‐Baylis‐Hillman Carbonates and α,β‐Unsaturated Aldehydes

Min

Seo

Ryu

et al. 2017

Bulletin Korean Chem Soc

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Spirooxindoles exist in a huge number of natural substances and pharmaceutically interesting compounds.1 Thus, tremendous efforts have been devoted to efficient protocols to access these important motifs over the past years. [1][2][3][4][5] Recently, we reported the synthesis of spirocyclohexadienyl-2-oxindoles by 6π-electrocyclic ring closure (6π-ERC) of the trienes, derived from Morita-Baylis-Hillman (MBH) adducts of cinnamaldehyde and isatin (Scheme 1).2e Very recently, we also reported the synthesis of dispirobisoxindole from MBH carbonates of N-methylisatin (Scheme 1).3 During the course of our study, we decided to examine the synthesis of structurally related spirocyclohexadienyl-2-oxindoles 4,5 with different substitution pattern by 6π-ERC of the trienes, derived from MBH carbonates of N-methylsatin and cinnamaldehyde, as shown in Scheme 1.At the outset of our experiment, the reaction of MBH carbonate 1a and trans-cinnamaldenyde (2a, 1.1 equiv) in 1,2-dichlorobenzene (ODCB) was examined at 150 C in the presence of PPh 3 (1.0 equiv).3 To our delight, spirocyclohexa-2,4-dienyl-2-oxindole 3a was obtained in good yield (69%) in short time (2 h). The formation of the other diastereomer (3a 0 , vide infra, Scheme 2) was not observed. The structure of 3a was unequivocally confirmed by its crystal structure (vide infra, Scheme 2).6 However, two diastereomeric dispirobisoxindoles (see, Scheme 1) have been formed as side products in appreciable yield (23%), as in our previous paper.3 When we carried out the reaction in refluxing p-xylene (5 h), the yield of 3a increased to 74%, and the yield of dispirobisoxindoles decreased (18%). The yield of 3a increased slightly (77%) when we carried out the reaction in refluxing toluene; however, a long reaction time (24 h) was required. When we used an excess amount of 2a (2.0 equiv) in refluxing xylene (5 h), the yield of 3a increased up to 85%. In the reaction mixture, the formation of only a trace amount (<5%) of dispirobisoxindole was observed. 7Encouraged by the results we synthesized various spirooxindoles 3b-3l, and the results are summarized in Table 1. Various spirooxindoles 3b-3e were synthesized in good to moderate yields (67-89%) by the reactions of substituted isatin derivatives 1b-1e with 2a. The reaction of 1a and trans-3-(2-furyl)acrolein (2b) afforded 3f in moderate yield (60%). The reaction of crotonaldehyde (2c) gave 3g in good yield (78%). In the reaction, we used an excess amount of 2c (3.0 equiv) because the boiling point of 2c (104 C) was lower than the reaction temperature (138 C). The reactions of 1a with α-methyl-trans-cinnamaldehyde (2d) and α-bromocinnamaldehyde (2e) afforded 3h and 3i in good yields (68% and 84%, respectively). However, the reactions with α-substituted aliphatic aldehydes, trans-2-methyl-2-butenal (2f) and 1-cyclohexene-1-carboxaldehyde (2g), produced the corresponding spirooxindoles 3j (23%) and 3k (33%) in low yields with 3.0 equiv. of 2f or 2g. The result might be due to sluggish reactivity in the Wittig reaction of α-branched α...

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“…The highly-substituted, stereo-congested, five-membered carbocycle containing contiguous stereocenters is one of the most common structural features in many structurally complicated, biologically important natural products [1][2][3][4][5][6][7] (Figure 1). Meanwhile, the construction of quaternary carbon stereocenter(s) is, at present, a distinct challenge in modern synthetic chemistry [8][9][10][11]. Therefore, the synthesis of highly-substituted five-membered carbocycles bearing congested arrays of stereocenters within the polycyclic framework of complex natural products usually require a sophisticated synthetic planning.…”

Section: Introductionmentioning

confidence: 99%

All-carbon [3 + 2] cycloaddition in natural product synthesis

Wang¹,

Liu²

2020

Beilstein J. Org. Chem.

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Many natural products possess interesting medicinal properties that arise from their intriguing chemical structures. The highly-substituted carbocycle is one of the most common structural features in many structurally complicated natural products. However, the construction of highly-substituted, stereo-congested, five-membered carbocycles containing all-carbon quaternary center(s) is, at present, a distinct challenge in modern synthetic chemistry, which can be accessed through the all-carbon [3 + 2] cycloaddition. More importantly, the all-carbon [3 + 2] cycloaddition can forge vicinal all-carbon quaternary centers in a single step and has been demonstrated in the synthesis of complex natural products. In this review, we present the development of all-carbon [3 + 2] cycloadditions and illustrate their application in natural product synthesis reported in the last decade covering 2011–2020 (inclusive).

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Enantioselective Construction of All‐Carbon Quaternary Stereogenic Centers by Using Phosphine Catalysis

Cited by 104 publications

References 112 publications

Enantioselective [4+2] Annulation to the Concise Synthesis of Chiral Dihydrocarbazoles

Enantioselective [4+2] Annulation to the Concise Synthesis of Chiral Dihydrocarbazoles

Synthesis of Spirocyclohexadieneyl‐2‐Oxindoles by 6π‐Electrocyclization of Trienes Derived from Wittig Reaction of Morita‐Baylis‐Hillman Carbonates and α,β‐Unsaturated Aldehydes

All-carbon [3 + 2] cycloaddition in natural product synthesis

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