First asymmetric decarboxylative cyanomethylation of isatins is reported herewith using bifunctional thiourea derived from l-proline in good yields and enantioselectivities. This strategy enables the construction of various 3-cyanomethylene substituted 3-hydroxyoxindoles in enantioselective manner. Enantioselective synthesis of CPC-1 alkaloid has been accomplished in fewer steps.
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http://dx.doi.org/10.1039/c4ob00271g | DOI Listing |
Org Lett
December 2024
Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, South Korea.
Enamides have emerged as robust alternatives for enamines, exhibiting versatile reactivity for further synthetic modifications, including nucleophilic addition, cycloaddition, and asymmetric hydrogenation. While transition-metal-catalyzed cross-coupling of alkenyl (pseudo)halides with amides has been widely employed to construct this valuable scaffold, it suffers from some limitations, such as the need for transition-metal catalysts and the preparative synthesis of alkenyl (pseudo)halides. In this study, we report a mild and convenient stereoretentive decarboxylative amidation of α,β-unsaturated carboxylic acids with easily procurable 1,4,2-dioxazol-5-ones, providing a practical synthetic route to enamides.
View Article and Find Full Text PDFChem Sci
January 2025
Frontier Institute of Science and Technology (FIST), Xi'an Jiaotong University Yanxiang Road 99 Xi'an 710045 China
The first Ni-catalyzed asymmetric decarboxylative strategy for the construction of carbocycles with contiguous quaternary all-carbon stereocenters is reported. The key to the success of these reactions is the utilization of rationally designed allenylic methylene cyclic carbonates as substrates with Ni catalysis. The floppy allenylic group exerts unique electronic properties on the carbonate, which allows further asymmetric nucleophilic annulations with alkenes.
View Article and Find Full Text PDFOrg Lett
December 2024
Institut für Chemie, Universität Oldenburg, D-26129 Oldenburg, Germany.
Optically active spirocycles were prepared in a sequence of two palladium-catalyzed reactions. In the first step, racemic α-(-iodophenyl)-β-oxo allyl esters were submitted to the palladium-catalyzed decarboxylative asymmetric allylic alkylation reaction, furnishing the α-allylated products with a quaternary stereocenter with good yields and enantioselectivities. Subsequently, these intermediate products were converted in a Heck reaction yielding the spirocyclic structures as a mixture of - and -cyclic regioisomers.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Euphorbialoid A () belongs to the rare diterpenoid family of premyrsinanes and exhibits potent anti-inflammatory effects. The 5/7/6/3-membered carbocycle (ABCD-ring) of contains 11 contiguous stereocenters and seven oxygen-containing functional groups. Moreover, four of the six hydroxy groups of are concentrated in the southern sector and flanked by four structurally different acyl groups.
View Article and Find Full Text PDFJ Org Chem
January 2025
Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur Campus, Kalyani, Nadia,West Bengal 741 246, India.
The asymmetric syntheses of naturally occurring biologically relevant -abietane diterpenoids, (-)-taiwaniaquinone G (), and H () have been reported via a chiral pool strategy starting from commercially available abietic acid. A ring contraction of the middle ring of the [6,6,6]-carbotricyclic abietane diterpenoid core was carried out under the Wolff rearrangement. Finally, the synthesis of (-)-taiwaniaquinone H () was completed via a one-pot CAN-mediated oxidative decarboxylation.
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