Reductive direct substitution of α-arylvinyl triflates on the sp carbon atom by magnesium in the presence of chlorosilane proceeded to give the corresponding α-silylstyrenes, which could not be reduced further, and the reaction completely stopped because the reduction potential of α-silylstyrenes lies out of the reducible field of magnesium. The subsequent reduction of α-silylstyrenes by calcium brought about the second introduction of another silyl group to the vicinal carbon atom to lead a selective and simple route to a variety of 1,2-disilanes from vinyl triflates by cooperative works of magnesium and calcium with different reduction potentiality.
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http://dx.doi.org/10.1021/acs.orglett.4c04321 | DOI Listing |
Org Lett
January 2025
Department of Materials Science and Bioengineering, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, NagaokaNiigata 940-2188, Japan.
Reductive direct substitution of α-arylvinyl triflates on the sp carbon atom by magnesium in the presence of chlorosilane proceeded to give the corresponding α-silylstyrenes, which could not be reduced further, and the reaction completely stopped because the reduction potential of α-silylstyrenes lies out of the reducible field of magnesium. The subsequent reduction of α-silylstyrenes by calcium brought about the second introduction of another silyl group to the vicinal carbon atom to lead a selective and simple route to a variety of 1,2-disilanes from vinyl triflates by cooperative works of magnesium and calcium with different reduction potentiality.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Department of Chemistry, School of Pharmacy, Air Force Medical University, Xi'an, 710032, China.
An efficient synthesis of continuously substituted quinoline derivatives palladium-catalyzed intramolecular 6- imidoylative cyclization of -alkenyl aryl isocyanides with (hetero)aryl halides or vinylic triflates has been developed. The reaction proceeds through the concerted metalation-deprotonation (CMD) mechanism by activation of a vinyl C-H bond with imidoylpalladium assisted by the carboxylate.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, Sidho-Kanho-Birsha University, Purulia 723104, W.B., India.
Distinctive, green, innovative, and well-organized photoinduced (metal- or photocatalyst-free) regioselective decarbonylative and decarboxylative C-O bond functionalization protocols to access aryl 2-aminobenzoates and 2-substituted benzoxazinone derivatives in excellent yields have been devised. These are achieved through the chemoselective scission of isatoic anhydride with ketones, diaryliodonium triflate, nitroalkene, phthalazinone, and phenol derivatives, which, in turn, served as the representative "electrophilic and nucleophilic" coupling partners. Control experiments and DFT calculations reveal that electrophilic radical-bearing coupling partners specifically follow the decarbonylation pathway, while nucleophilic radical-bearing conjugates facilitate the decarboxylation process.
View Article and Find Full Text PDFJACS Au
November 2024
Laboratory of Medicinal Chemical Biology, Department of Medicinal Chemistry, College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou 215123, China.
(-)-Pleurotin () and (+)-dihydropleurotinic acid () are benzoquinone meroterpenoids isolated from fungal sources with powerful antitumor and antibiotic activities. Concise asymmetric total syntheses of the stereochemically pure (+)-dihydropleurotinic acid () and (-)-pleurotin () from the chiral pool ()-Roche ester-derived vinyl bromide have been achieved in 12 and 13 longest linear steps, respectively. The key transformations feature a Michael addition/alkylation cascade reaction to forge three contiguous stereocenters matched with the natural products, a PtO-catalyzed stereoselective reduction of olefin to generate the correct stereocenter at C3, a palladium-catalyzed Negishi cross-coupling between triflate and zinc reagent to introduce the redox-sensitive para-quinone moiety, and a hydroboration/copper-catalyzed carboxylation sequence to incorporate the vital carboxyl group.
View Article and Find Full Text PDFOrg Lett
November 2024
Institute of Organic Chemistry, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany.
In this report, we describe a simple method for the synthesis of 2-aryl-2-vinyl-cyclobutanones through the reaction of in situ generated cyclopropanones and cinnamylsulfonium ylides, representing an example of a formal carbene insertion into these three-membered rings. The cyclobutanones thus obtained are ideal substrates for palladium-catalyzed coupling reactions upon enol triflate formation, thereby providing access to densely functionalized cyclobutenes. A mechanistic proposal for the ring-enlargement is presented based on experimental evidence.
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