An efficient approach for the construction of trifluoromethylated all-carbon quaternary stereocenters: enantioselective Ni(<scp>ii</scp>)-catalyzed Michael addition of 2-acetyl azaarene to β,β-disubstituted nitroalkenes

Hou, Xuhe; Ma, Hongli; Zhang, Zhenhua; Xie, Lei; Qin, Zhaohai; Fu, Bin

doi:10.1039/c5cc08480f

Cited by 41 publications

(16 citation statements)

References 45 publications

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“…The methodology could then be extended to the formation of quaternary centers (Scheme 15). [20,21] Wang and co-workers have described in 2017 the use of αsubstituted acyl-imidazoles 33 (if R 1 ¼ 6 H, Scheme 16). High anti diastereoselectivities, associated with excellent enantioselectiv-Scheme 12.…”

Section: α-Functionalization Through Acyl-imidazole Enolatesmentioning

confidence: 99%

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

et al. 2019

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Since the first report by Evans in asymmetric Friedel-Crafts reactions, the use of acyl-imidazoles has blossomed as powerful ester/amide surrogates. The imidazole scaffold indeed displays stability and special activation features allowing both better reactivity and selectivity in traditional ester/amide functionalizations: α-(enolate chemistry), β-(conjugate additions), α,β-(cyclo-additions) or γ/δ-(vinylogous). An overview of the contemporary and growing interest in acyl-imidazoles in metal-and organo-catalyzed transformations (bio-hybrid catalytic systems will be fully described in a back-to-back Minireview) will be highlighted. Moreover, post-functionalization expediencies are also going to be discussed in this Minireview. Scheme 1. Synthesis of acyl-imidazoles by Okamoto and co-workers.Scheme 2. Synthesis of α,β-unsaturated acyl-imidazoles. . α-Alkylation of 2-naphthylmethyloxy acyl-imidazoles through PTC catalysis. NPM = 2-naphthylmethyl.Scheme 47. Chemo-and enantioselective oxidative cycloetherification of 2acyl-imidazoles with chiral quaternary ammonium salts. (please, change the chemdraw scheme 47; a new one is given) Scheme 48. Organocatalyzed enantioselective conjugate addition of aryl trifluoroborate to α,β-unsaturated 2-acyl 1-methylimidazole. 2 3 4 5 6 7 8

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Section: α-Functionalization Through Acyl-imidazole Enolatesmentioning

confidence: 99%

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

et al. 2019

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“…Thus, the diastereoisomeric secondary alcohols 5a and 5b were readily obtained in a ratio of 1.2:1 and in a combined yield of 84% with 96% ee (for both isomers) by reduction of the carbonyl in 3ca with NaBH 4 (Scheme b). When 3ca was treated with Fe and AcOH in THF/MeOH at 65 °C, the pyrroline derivative 6 was produced in a good yield without any loss of enantioselectivity (Scheme b). The formation of 6 includes reduction of NO 2 to NH 2 and subsequent intramolecular condensation between CO and NH 2 .…”

Section: Resultsmentioning

confidence: 99%

Asymmetric Michael Addition of 2-Acetyl Azaarenes to β-CF₃-β-(3-indolyl)nitroalkenes Catalyzed by a Cobalt(II)/(imidazoline-oxazoline) Complex

Zhu

Gong

et al. 2018

J. Org. Chem.

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The first enantioselective Michael addition of 2-acetyl azaarenes to β-CF 3 -β-(3-indolyl)nitroalkenes has been successfully achieved in the presence of a Co(II)/ (imidazoline-oxazoline) complex as the catalyst. The reaction affords a series of CF 3 -and 3-indole-containing adducts featuring a trifluoromethylated all-carbon quaternary stereocenter in good to excellent yields (up to 99%) and enantioselectivities (up to 96% ee). Furthermore, the functional groups in the adducts including CO, NO 2 , and the azaarene provide a large variety of useful transformations, leading to the formation of valuable intermediates such as optically active secondary alcohol, pyrroline, ester, and pyrrolidinone which all contain a 3-substituted indole and a trifluoromethylated all-carbon quaternary stereocenter.

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“…[6] Afterwards, other research groups extended the potential of the concept. [7] Fu and coworkers described the first enentioselective Michael addition of 2-acetyl azaarenes 40 to β-CF 3 -βdisubstituted nitroalkenes 41. The reaction catalyzed by chiral Ni(acac) 2 -bisoxazoline complex affords compounds containing trifluoromethylated all-carbon quaternary stereocenters 42 in good yields with ee up to > 99%.…”

Section: Azaarenes With a Carbonyl Group Between The Heterocycle And mentioning

confidence: 99%

Enantioselective Synthesis of Alkyl Azaarenes

Meazza

Rios

2019

Asian J Org Chem

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This Minireview covers reports on the enantioselective synthesis of alkyl azaarenes since 2014. It deals with the latest achievements on the reactivity of alkyl azaarenes aiming at the preparation of more complex azaarenes containing chiral centers. They rely on the activating properties of the nitrogen atom when opportunely coordinated with a metal complex or Brønsted acid and possibly containing chiral ligands. In addition, conveniently located electron-withdrawing activating functional groups help increase the reactivity of the azaarenes. The same concepts operate in the case of vinyl azaarenes.[a] Dr. Scheme 1. Modes of activationScheme 2. Early example by Lam. 2 3 4 5 6 7 8

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An efficient approach for the construction of trifluoromethylated all-carbon quaternary stereocenters: enantioselective Ni(ii)-catalyzed Michael addition of 2-acetyl azaarene to β,β-disubstituted nitroalkenes

Cited by 41 publications

References 45 publications

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

Asymmetric Michael Addition of 2-Acetyl Azaarenes to β-CF₃-β-(3-indolyl)nitroalkenes Catalyzed by a Cobalt(II)/(imidazoline-oxazoline) Complex

Enantioselective Synthesis of Alkyl Azaarenes

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An efficient approach for the construction of trifluoromethylated all-carbon quaternary stereocenters: enantioselective Ni(ii)-catalyzed Michael addition of 2-acetyl azaarene to β,β-disubstituted nitroalkenes

Cited by 41 publications

References 45 publications

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

Acyl‐Imidazoles: A Privileged Ester Surrogate for Enantioselective Synthesis

Asymmetric Michael Addition of 2-Acetyl Azaarenes to β-CF3-β-(3-indolyl)nitroalkenes Catalyzed by a Cobalt(II)/(imidazoline-oxazoline) Complex

Enantioselective Synthesis of Alkyl Azaarenes

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Asymmetric Michael Addition of 2-Acetyl Azaarenes to β-CF₃-β-(3-indolyl)nitroalkenes Catalyzed by a Cobalt(II)/(imidazoline-oxazoline) Complex