With the aid of a class of newly discovered Trost-type bisphosphine ligands bearing a chiral cycloalkane framework, the Pd-catalyzed decarboxylative dearomative asymmetric allylic alkylation (AAA) of benzofurans was achieved with high efficiency [0.2-1.0 mol% Pd(dba)/], good generality, and high enantioselectivity (>30 examples, 82-99% yield and 90-96% ee). Moreover, a diversity-oriented synthesis (DOS) of previously unreachable flavaglines is disclosed. It features a reliable and scalable sequence of the freshly developed Tsuji-Trost-Stoltz AAA, a Wacker-Grubbs-Stoltz oxidation, an -benzoin condensation, and a conjugate addition, which allows the efficient construction of the challenging and compact cyclopenta[]benzofuran scaffold with contiguous stereocenters. This strategy offers a new avenue for developing flavagline-based drugs.
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http://dx.doi.org/10.1021/jacs.0c05113 | DOI Listing |
J Am Chem Soc
November 2024
School of Pharmacy, Fudan University, Shanghai, China, 201203.
Norzoanthamine is a structurally complex polycyclic natural product that expresses a broad range of biological activities, rendering facile access to it and its analogs of considerable importance in drug discovery and development. However, strategies for efficient access to this class of marine alkaloids remain lacking. Here, we report a strategy, characterized by three key photochemical reactions, that we used to synthesize norzoanthamine in 16 steps.
View Article and Find Full Text PDFOrg Lett
November 2024
Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan 410081, China.
Until now, palladium-catalyzed dearomative Heck reactions of indoles were largely limited to β-H elimination and nucleophilic capture of the transient alkyl-Pd(II) species. Herein, we disclose a novel palladium-catalyzed dearomative Heck/C(sp)-H activation/decarboxylative cyclization of C2-tethered indoles. In this protocol, the alkyl-Pd(II) species formed by dearomatization of C2-tethered indoles is not terminated by common β-H elimination or nucleophilic capture, but rather generates ,-palladacycle via C-H activation.
View Article and Find Full Text PDFOrg Lett
October 2024
Department of Analytical & Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
Here we report the development of unprecedented silver-catalyzed intramolecular annulations of -acrolyl-2-(3-indolyl) benzimidazoles with alkyl carboxylic acids to construct complex fused-pentacyclic alkaloid scaffolds. Divergent reactivities are noticed with altered groups at C2-indole of the substrate. The reaction proceeds through decarboxylative alkylation, followed by dearomative annulation in a domino manner with excellent diastereoselectivity.
View Article and Find Full Text PDFOrg Lett
January 2024
Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
A metal-free oxidative intramolecular dearomative spirocyclization of indole-3-formyl-2-carboxamides has been developed for the first time, affording spiropseudoindoxyls in good yields. This domino process proceeds through sequential oxidation, decarboxylation and -arylation. The unique feature of this approach includes the compatibility of -protected-indole-2-carboxamides.
View Article and Find Full Text PDFJ Am Chem Soc
November 2023
The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Aleutianamine is a recently isolated pyrroloiminoquinone natural product that displays potent and selective biological activity toward human pancreatic cancer cells with an IC of 25 nM against PANC-1, making it a potential candidate for therapeutic development. We report a synthetic approach to aleutianamine wherein the unique [3.3.
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