A cinchona alkaloid-catalyzed, highly enantioselective, alpha-amination of oxindoles has been developed. The reaction is general, operationally simple, and affords the desired products in high yields with good to excellent enantioselectivity. Significantly, this study provides a general catalytic method for the construction of a C-N bond at the C3 position of oxindoles as well as for the creation of a nitrogen-containing, tetrasubstituted chiral center.
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http://dx.doi.org/10.1021/jo902039a | DOI Listing |
Nat Commun
May 2024
Henan Key Laboratory of Chemical Biology and Organic Chemistry, College of Chemistry, Zhengzhou University, Zhengzhou, China.
Chirality constitutes an inherent attribute of nature. The catalytic asymmetric synthesis of molecules with central, axial, and helical chirality is a topic of intense interest and is becoming a mature field of research. However, due to the difficulty in synthesis and the lack of a prototype, less attention has been given to planar chirality arising from the destruction of symmetry on a single planar ring.
View Article and Find Full Text PDFJ Am Chem Soc
March 2024
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
Methods to access chiral sulfur(VI) pharmacophores are of interest in medicinal and synthetic chemistry. We report the desymmetrization of unprotected sulfonimidamides via asymmetric acylation with a cinchona-phosphinate catalyst. The desired products are formed in excellent yield and enantioselectivity with no observed bis-acylation.
View Article and Find Full Text PDFChem Commun (Camb)
October 2021
Department of Chemistry, University of Massachusetts, 100 Morrissey Boulevard, Boston, MA 02125, USA.
Organocatalysis has unique modes of activation, mild reaction conditions, and good catalyst structural amenability. The integration of green techniques such as catalyst recovery and one-pot reactions makes organocatalysis more efficient and attractive. Presented in this article are the recyclable cinchona alkaloid-catalyzed reactions including fluorination and Michael addition-initiated cascade reactions in asymmetric synthesis of functionalized compounds of biological interest.
View Article and Find Full Text PDFJ Am Chem Soc
January 2021
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States.
The cinchona-alkaloid-catalyzed cycloaddition reactions of 2-cyclohexenone with tropone and various heptafulvenes give [8+2] or [4+2] cycloadducts, depending on the substituents present on the heptafulvene. We report the results of new experiments with heptafulvenes, containing diester and barbiturate substituents, which in combination with computational studies were performed to elucidate the factors controlling [8+2] vs [4+2] cycloaddition pathways, including chemo-, regio-, and stereoselectivities of these higher-order cycloadditions. The protonated cinchona alkaloid primary amine catalyst reacts with 2-cyclohexenone to form a linear dienamine intermediate that subsequently undergoes a stepwise [8+2] or [4+2] cycloaddition.
View Article and Find Full Text PDFACS Catal
June 2018
Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182, United States.
We report a cinchona alkaloid catalyzed addition of thiophenol into rapidly interconverting aryl-naphthoquinones, resulting in stable biaryl atropisomers upon reductive methylation. An array of thiophenols and naphthoquinone substrates were evaluated, and we observed selectivities up to 98.5:1.
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