α-Keto hydrazones and α,β-unsaturated γ-keto hydrazones are suitable pro-nucleophiles for asymmetric cross-aldol reactions with trifluoromethyl ketones aza-di(tri)enamine-type intermediates. A quinidine-derived primary amine catalyst affords tertiary trifluoromethylated alcohols in good-to-excellent yields and high enantioselectivities. Subsequent transformations of hydrazono moieties yield appealing fluorinated carboxylic acids, 1,4-dicarbonyls and γ-keto acids.
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http://dx.doi.org/10.1039/d1cc05014a | DOI Listing |
Org Lett
June 2024
Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
We have successfully accomplished a catalytic asymmetric total synthesis of entecavir, a first-line antihepatitis B virus medication. The pivotal aspect of our strategy lies in the utilization of a Pd-catalyzed enyne borylative cyclization reaction, enabling the construction of a highly substituted cyclopentene scaffold with exceptional stereoselectivity. Additionally, we efficiently accessed the crucial 1,3-diol enyne system early in our synthetic route through a diarylprolinol organocatalyzed enantioselective cross-aldol reaction and Re-catalyzed allylic alcohol relocation.
View Article and Find Full Text PDFThe Mukaiyama aldol reaction is generally a Lewis-acid catalyzed cross-aldol reaction between an aldehyde or ketone and silyl enol ether. It was first described by Mukaiyama in 1973, almost 5 decades ago, to achieve the enantioselective synthesis of β-hydroxy carbonyl compounds in high percentage yields. Mukaiyama aldol adducts play a pivotal role in the synthesis of various naturally occurring and medicinally important organic compounds such as polyketides, alkaloids, macrolides, This review highlights the significance of the Mukaiyama aldol reaction towards the asymmetric synthesis of a wide range of biologically active natural products reported recently (since 2020).
View Article and Find Full Text PDFRSC Adv
January 2023
Division of Sustainable and Environmental Engineering, Graduate School of Engineering, Muroran Institute of Technology 27-1 Mizumoto-cho Muroran 050-8585 Japan
Distinct types of new boron fused primary amino amide organocatalysts were designed and synthesized from commercially available amino acids. Their catalytic activities were investigated in asymmetric crossed aldol reaction of ketones with aromatic aldehydes to afford the corresponding chiral -aldol adducts with good chemical yields, moderate diastereoselectivity and good to excellent enantioselectivities (up to 94% yields, up to 90 : 10 dr, up to 94% ee).
View Article and Find Full Text PDFBioorg Chem
December 2022
School of Chemical Sciences, Goa University, Taleigao Plateau, Goa 403206 India. Electronic address:
A new series of syn-functionalised chiral hydroxy pyrrolidines and pyrrolidones containing α,β-contiguous stereocenters were synthesized via a diphenylprolinol-catalysed asymmetric cross aldol reaction. The synthesized compounds were characterised and evaluated for their α-glucosidase inhibitory potential. The hydroxy pyrrolidine series (9a-9i) was found to be selectively more potent against the α-glucosidase enzyme as compared to the pyrrolidone series (10a-10i).
View Article and Find Full Text PDFChem Rec
July 2023
Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi, 980-8578, Japan.
The aldol reaction is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Asymmetric direct cross-aldol reaction of two different aldehydes has been regarded as a difficult reaction because of the side reactions such as self-aldol reaction and over reaction. We found that trifluoromethyl-substituted diarylprolinol, α,α-bis[3,5-bis(trifluoromethyl)phenyl]-2-pyrrolidinemethanol (1), is an effective organocatalyst that promotes several cross-aldol reactions of aldehydes with excellent diastereo- and enantioselectivities.
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