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Vicinal oxygen‐containing tetra‐ and tri‐substituted stereocenters exist widely in chromanone lactone and tetrahydroxanthone natural products. Their enantioselective construction in a single step remains elusive and poses a formidable challenge for chemical synthesis. Here, we report the first copper(I)‐catalyzed asymmetric vinylogous additions of siloxyfurans to 2‐ester‐substituted chromones, which enable concise and enantioselective assembly of chromanone lactones. Both syn and anti adducts can be accessed with excellent diastereo‐ and enantioselectivity by judicious choice of the chiral ligands. Our approach allowed for the efficient synthesis of (−)‐blennolide B with precise stereochemical control, which provides a formal synthesis of secalonic acid A. [ABSTRACT FROM AUTHOR]

Rocaglaol, a representative flavagline, has attracted significant attention because of its unique chemical structure and biological activities. This paper reports a mild and scalable copper‐catalyzed enantioselective conjugate addition of benzofuran‐3(2H)‐ones to α,β‐unsaturated thioamides. This method allows for the concise synthesis of all possible stereoisomers of a key intermediate of rocaglaol and its derivatives in a highly diastereo‐ and enantioselective manner using different chiral phosphine ligands. Theoretical insights into the reaction mechanism and the origin of ligand‐dependent diastereodivergence were obtained using density functional theory calculations. [ABSTRACT FROM AUTHOR]

Abstract: The direct catalytic asymmetric aldol reaction is an emerging catalytic methodology that provides atom‐economical access to functionalized chiral building blocks. Thioamides are useful aldol donors due to their high‐fidelity chemoselective enolization and divergent post‐aldol transformations. Herein we describe the incorporation of an α‐vinyl appendage on a thioamide, which expands the utility of aldol adducts for natural product synthesis. This vinylated thioamide was not accommodated under the previously identified catalyst settings, but the newly developed catalytic conditions furnished aldol products containing the pendant vinyl group. [ABSTRACT FROM AUTHOR]

Total synthesis of leucinostatin A, a modulator of tumor-stroma interactions, using asymmetric catalyses, a nitroaldol reaction, thioamide-aldol reaction, Strecker-type reaction, and alcoholysis of 3-methylglutaric anhydride, is described. We demonstrated the applicability of the established catalytic asymmetric processes to the synthesis of molecules with a complex structure. Careful analysis of the NMR data, HPLC profiles, and biological activity revealed that the correct structure of leucinostatin A is the epimeric form of the reported structure; the secondary alcohol within the AHMOD residue has an R configuration. [ABSTRACT FROM AUTHOR]

Four new macrolactones, leptolyngbyolides A-D, were isolated from the cyanobacterium Leptolyngbya sp. collected in Okinawa, Japan. The planar structures of leptolyngbyolides were determined by extensive NMR studies, although complete assignment of the absolute configuration awaited the catalytic asymmetric total synthesis of leptolyngbyolide C. The synthesis took advantage of the catalytic asymmetric thioamide-aldol reaction using copper(I) complexed with a chiral bidentate phosphine ligand to regulate two key stereochemistries of the molecule at the outset. The present total synthesis demonstrates the utility of this reaction for the construction of complex chemical entities. In addition to the total synthesis, this work reports that leptolyngbyolides depolymerize filamentous actin (F-actin) both in vitro and in cells. Detailed biological studies suggest the probable order of F-actin depolymerization and apoptosis caused by leptolyngbyolides. [ABSTRACT FROM AUTHOR]

Asymmetric Catalysis, Conjugate Addition, Enolates, Natural Products, Total Synthesis Keywords: Asymmetric Catalysis; Conjugate Addition; Enolates; Natural Products; Total Synthesis EN Asymmetric Catalysis Conjugate Addition Enolates Natural Products Total Synthesis 1 1 1 06/22/22 20220627 NES 220627 B Enantiomerenangereicherte Chromanonlactone b wurden durch kupferkatalysierte asymmetrische vinyloge Addition von Siloxyfuranen an 2-Ester-substituierte Chromone hergestellt, wie Jin Cui, Masakatsu Shibasaki et al. in ihrer Zuschrift berichten (e202203128). Innenrücktitelbild: Concise and Stereodivergent Approach to Chromanone Lactones through Copper-Catalyzed Asymmetric Vinylogous Addition of Siloxyfurans to 2-Ester-Substituted Chromones (Angew. [Extracted from the article]

Inside Back Cover: Concise and Stereodivergent Approach to Chromanone Lactones through Copper-Catalyzed Asymmetric Vinylogous Addition of Siloxyfurans to 2-Ester-Substituted Chromones (Angew. Asymmetric Catalysis, Conjugate Addition, Enolates, Natural Products, Total Synthesis Keywords: Asymmetric Catalysis; Conjugate Addition; Enolates; Natural Products; Total Synthesis EN Asymmetric Catalysis Conjugate Addition Enolates Natural Products Total Synthesis 1 1 1 06/22/22 20220627 NES 220627 B Enantioenriched chromanone lactones b were prepared by copper-catalyzed asymmetric vinylogous addition of siloxyfurans to 2-ester-substituted chromones, as reported by Jin Cui, Masakatsu Shibasaki, and co-workers in their Communication (e202203128). [Extracted from the article]