Amphiphilic fluorocarbons have unique properties that facilitate their self assembly and adhesion to both inorganic and biological substrates. Incorporation of these moieties into valuable constructs typically require complex synthetic routes that have limited their use. Here, the base-catalyzed diastereoselective synthesis of 6-methyl-2,4,6-tris(trifluoromethyl)tetrahydro-2H-pyran-2,4-diol is reported. Trimerization of trifluoroacetone in the presence of 5 mol% KHMDS delivers one of four diastereomers selectively in 81% yield with no column chromatography. Temperature screening revealed the reversibility of this trimerization and the funneling of material into the most thermodynamically stable oxane. Subsequent functionalization with boronic acids is reported.
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http://dx.doi.org/10.1039/c7ob01094j | DOI Listing |
Chem Commun (Camb)
December 2024
Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Angew Chem Int Ed Engl
November 2024
Department of Chemistry, Indian Institute of Technology Jammu, Jagti, NH-44, Nagrota Bypass, Jammu J&K, 181221, India.
The development of Michael addition reactions to conjugated cyclopropenes is a challenge in organic synthesis due to the fleeting and reactive nature of such strained Michael acceptor systems. Herein, the development of a photochemical approach towards such conjugated cyclopropenes is reported that serves as a strategic entry point to densely functionalized cyclopropanes in a diastereoselective fashion. The process involves the light-mediated generation of transient cyclopropenyl α,β-unsaturated esters from vinyl diazo esters, followed by an organic base catalyzed nucleophilic addition of N-heterocycles to directly access β-N-heterocyclic cyclopropanoic esters.
View Article and Find Full Text PDFOrg Biomol Chem
November 2024
Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Key Laboratory of Flexible Electronics, Fujian Normal University and Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou 350117, China.
Herein, an efficient, base catalyzed cascade vinylogous Michael/Michael cycloaddition reaction of α-alkylidene succinimides and oxindole-derived pyrazolones has been successfully developed. A variety of highly functionalized cyclopentanes fused with spirooxindoles were obtained in good yields, with excellent diastereoselectivities and exclusive vinylogous site-selectivities. This strategy represents the first example of α-alkylidene succinimides serving as nucleophilic reagents to trigger a vinylogous cascade reaction.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Department of Chemistry, Aarhus University, 8000, Aarhus C, Denmark.
The substituted tetrahydrofuran core is a structural motif in many biologically active and natural compounds. However, the scarcity of enantioselective methods developed towards its synthesis makes this field challenging and attractive to explore. Herein, the first Brønsted-base catalyzed enantioselective (3+2) annulation of donor-acceptor cyclopropanes with aldehydes and ketones affording enantioenriched 2,3,5-substituted tetrahydrofurans is reported.
View Article and Find Full Text PDFJ Org Chem
July 2024
Department of Chemistry, Savitribai Phule Pune University (Formerly University of Pune), Ganeshkhind, Pune 411007, India.
An efficient one-pot metal-free, base-catalyzed method has been developed for the regioselective [3 + 2]/[4 + 2] annulation reactions of electrophilic methyleneindolinones with haloalcohols to furnish spirooxindole derivatives under mild reaction conditions. This reaction afforded the corresponding products with two contiguous stereocenters including a quaternary center in good to excellent yield (up to 95%) with moderate to good diastereoselectivities (up to 12.5:1 ) with complete regioselectivity.
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