Asymmetric organocatalytic Michael addition of Meldrum’s acid to nitroalkenes: probing the mechanism of bifunctional thiourea organocatalysts

Kataja, Antti O.; Koskinen, Ari M. P.

doi:10.3998/ark.5550190.0011.216

Arkivoc

2010

DOI: 10.3998/ark.5550190.0011.216

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Asymmetric organocatalytic Michael addition of Meldrum’s acid to nitroalkenes: probing the mechanism of bifunctional thiourea organocatalysts

Antti O. Kataja¹,

Ari M. P. Koskinen²

Abstract: The asymmetric Michael addition of Meldrum's acid to nitroalkenes was studied using a novel type of Cinchona alkaloid-based bifunctional thiourea organocatalyst. The functionality of the thiourea catalysts was also probed by preparing and testing thiourea-N-methylated analogues of the well-known bis-(3,5-trifluoromethyl)phenyl-substituted catalyst.

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Cited by 3 publications

References 10 publications

(13 reference statements)

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Hydrogen-Bond-Donor-Directed Switching of Enantioselectivity in the Vinylogous Aldol–Cyclization Cascade Reaction of Prostereogenic 3-Alkylidene Oxindoles with Isatins and o-Quinones

et al. 2022

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In this study, we reported a hydrogen-bond-donor-directed enantiodivergent vinylogous aldol–cyclization cascade reaction of 3-alkylidene oxindoles with isatins and o-quinones. Both enantiomers can be prepared by thiourea or squaramide cinchona alkaloid bifunctional organocatalysts with the same quinine scaffold. Kinetic study data provided the possible reaction mechanism for the vinylogous aldol–cyclization cascade reaction. The DFT calculation data showed the geometry of the generated dienolates from pronucleophiles dominated the observed switch of enantioselectivity.

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Hydrogen-Bond-Donor-Directed Switching of Enantioselectivity in the Vinylogous Aldol–Cyclization Cascade Reaction of Prostereogenic 3-Alkylidene Oxindoles with Isatins and o-Quinones

et al. 2022

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Mass Spectra of New Heterocycles: XXV. Electron Ionization Study of N-[5-Aminothiophen-2-yl]thioureas

Клыба¹,

Sanzheeva²,

Nedolya³

et al. 2023

Russ J Org Chem

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Mass-spectra of new heterocycles: XXV. electron impact study of <i>N</i>-[5-amino-2-thienyl]thioureas

Klyba,

Sanzheeva,

Nedolya

et al. 2023

Žurnal organičeskoj himii

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The mass spectra of previously unknown N -(5-amino-2-thienyl)thioureas obtained in one preparative step from propargylamines and isothiocyanates were studied for the first time, and the main patterns of their fragmentation under electron ionization conditions (70 eV) were revealed. All thienylthioureas studied form a molecular ion ( I rel 7-61%), whose general direction of fragmentation {with the exception of N -[5-(diethylamino)-2-thienyl]- N , N '-diphenylthiourea} is the breaking of the R1N-C(=S) bond with the formation of the [ M - R2NHCS]+ ion, the peak of which has a high intensity ( I rel 35-85%). The dominant direction of fragmentation of the molecular ion N -[5-(diethylamino)-2-thienyl]- N , N '-diphenylthiourea is associated with the degradation of the thiophene cycle by C2-S and C4-C5 bonds. For N -(5-pyrrolidine-1-yl-2-thienyl)- and N -(5-piperidine-1yl-2-thienyl)thioureas are characterized by the course of intensive specific rearrangement processes, manifested in the appearance of unexpected channels of primary fragmentation of the molecular ion, the main of which is the elimination of the molecule N , N '-dimethylcarbodiimide.

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Asymmetric organocatalytic Michael addition of Meldrum’s acid to nitroalkenes: probing the mechanism of bifunctional thiourea organocatalysts

Cited by 3 publications

References 10 publications

Hydrogen-Bond-Donor-Directed Switching of Enantioselectivity in the Vinylogous Aldol–Cyclization Cascade Reaction of Prostereogenic 3-Alkylidene Oxindoles with Isatins and o-Quinones

Hydrogen-Bond-Donor-Directed Switching of Enantioselectivity in the Vinylogous Aldol–Cyclization Cascade Reaction of Prostereogenic 3-Alkylidene Oxindoles with Isatins and o-Quinones

Mass Spectra of New Heterocycles: XXV. Electron Ionization Study of N-[5-Aminothiophen-2-yl]thioureas

Mass-spectra of new heterocycles: XXV. electron impact study of <i>N</i>-[5-amino-2-thienyl]thioureas

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