The cinchona thiourea moiety in the self-assembled modularly designed organocatalysts (MDOs) switches off the iminium catalysis of these catalysts. In this study, it was found that the inhibited iminium catalysis could be switched on by using an appropriate weak acid and that, once the iminium catalysis was switched on, these catalysts could be applied for the highly stereoselective and diastereodivergent synthesis of 4-oxocyclohexanecarbaldehydes via a domino reaction between ketones and α,β-unsaturated aldehydes.
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http://dx.doi.org/10.1039/d1cc01020d | DOI Listing |
J Org Chem
January 2025
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Materials Sciences, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, P. R. China.
-Difluorohomoallyl amines, an important class of -difluoroalkenes, are prevalent moieties in many bioactive compounds. However, limited methods are suitable for the synthesis of this type of compound containing secondary amines. Here, we display a photocatalytic multicomponent protocol for the synthesis of -difluoroalkenes containing secondary amines, which makes use of readily available materials: arylamines, alkyl aldehydes, and α-trifluoromethyl alkenes.
View Article and Find Full Text PDFSci Adv
January 2025
State Key Laboratory of Organometallic Chemistry and Shanghai Hongkong Joint Laboratory in Chemical Synthesis, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032 (China).
Singly occupied molecular orbital (SOMO) activation of in situ generated enamines has achieved great success in (asymmetric) α-functionalization of carbonyl compounds. However, examples on the use of this activation mode in the transformations of other functional groups are rare, and the combination of SOMO activation with transition metal catalysis is still less explored. In the area of deoxygenative functionalization of amides, intermediates such as iminium ions and enamines were often generated in situ to result in the formation of α-functionalized amines.
View Article and Find Full Text PDFBeilstein J Org Chem
January 2025
Department of Organic Chemistry, Faculty of Natural Science, Comenius University Bratislava, Mlynská dolina, Ilkovičova 6, 842 15 Bratislava, Slovakia.
Axial chirality is present in a variety of naturally occurring compounds, and is becoming increasingly relevant also in medicine. Many axially chiral compounds are important as catalysts in asymmetric catalysis or have chiroptical properties. This review overviews recent progress in the synthesis of axially chiral compounds via asymmetric organocatalysis.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Wisconsin─Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
Hydrazides are known to catalyze reactions of α,β-unsaturated aldehydes via transient iminium formation. The iminium intermediate displays enhanced electrophilicity, which facilitates conjugate additions and cycloadditions. We observed that a hydrazide embedded in a seven-membered ring catalyzes homoaldol condensation of a simple aldehyde in a process that displays an approximate second-order dependence on the hydrazide.
View Article and Find Full Text PDFACS Catal
May 2024
Department of Chemistry, Boston University, Boston, MA 02215.
Foldamers, small synthetic peptides made of and -amino acids, have been found to be efficient catalysts for carbon-carbon bond-forming aldol reactions; of particular interest is their ability to catalyze macrocycle ring closure reactions. These catalysts feature a pair of amine groups that are aligned by the helical conformation and act in concert. Kinetic measurements show that the rate of the reaction depends on the identity of the amine side chains present.
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