α-Alkynyl-α'-trimethylsilylhydrazones are used as novel Rh(II)-carbenoids precursors. These new carbenoids have shown very good reactivity in Si-H insertion reactions, leading to original propargylic geminal-bis(silanes) in a two-step sequential process.
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http://dx.doi.org/10.1021/acs.orglett.6b02264 | DOI Listing |
Chem Commun (Camb)
December 2024
University of Turin - Department of Chemistry, Via Giuria 7, 10125, Turin, Italy.
The chemoselective synthesis of trisubstituted alkenyl halides (Cl, Br, F, I) starting from ketones and aldehydes and lithium halocarbenoids is reported. Upon forming the corresponding tetrahedral intermediate adduct, followed by the addition of thionyl chloride, a selective E2-type elimination is triggered, furnishing the targeted motifs. The transformation takes place under full chemocontrol: various sensitive functionalities ( ester, nitrile, nitro, or halogen groups) can be placed on the starting materials, thus documenting a wide reaction scope, as well as the application of the technique to biologically active substances.
View Article and Find Full Text PDFJ Org Chem
December 2024
Guangdong Provincial Key Laboratory of Chiral Molecules and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China.
A solvent-controlled Rh(III)-catalyzed mono- and dual-C-H bond activation/carbene migratory insertion with diazo compounds as a single coupling partner was demonstrated. The reaction proceeded under mild conditions, yielding products in good to excellent yields. These results are significant for the development of the domino multiple functionalization of C(sp)-H bonds via a carbenoid insertion approach.
View Article and Find Full Text PDFChemistry
November 2024
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, No. 381, Wushan Road, Tianhe district, Guangzhou, 510641, China.
α-Diazoesters belong to significantly important carbenoid precursors in synthetic chemistry. Diazomethylation-based difunctionalization of alkenes is highly valuable but remain nontrivial. Herein, we reported a general and modular approach for the direct 1,2-oxydiazomethylation of alkenes through visible-light photoredox catalysis.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, South Korea.
Transition metal carbenes have emerged as versatile intermediates for various types of alkylations. While reactions of metal carbene species with alkenes have been extensively studied, most examples focus on cyclopropanation and allylic C-H insertion. Herein, we present the first example of a catalytic strategy for the carbene-involved regioselective remote C-H alkylation of internal olefins by synergistically combining two iridium-mediated reactivities of olefin chain walking and carbenoid migratory insertion.
View Article and Find Full Text PDFChem Asian J
October 2024
Department of Chemistry, Indian Institute of Science Education & Research, 462066, Bhopal, Madhya Pradesh, India.
A new approach for the synthetically important γ-functionalized enals has been developed. The strategy involves rhodium-catalyzed direct C-C & C-S bond forming site-selective γ-difunctionalization of diazoenals with aryl propargyl sulfides via sulfur ylide [2,3] sigmatropic rearrangement, resulting in the highly functionalized γ-allenyl(sulfanyl)enals in excellent yield at ambient temperature. This highly versatile approach constitutes a viable alternative to the remote carbonyl-directed γ-functionalization of unmodified enals which suffer from competitive side reactions.
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