Rhodium-Catalyzed Enantioselective Formal [4+1] Cyclization of Benzyl Alcohols and Benzaldimines: Facile Access to Silicon-Stereogenic Heterocycles.

The carbon-to-silicon switch in formation of bioactive sila-heterocycles with a silicon-stereogenic center has garnered significant interest in drug discovery. However, metal-catalyzed synthesis of such scaffolds is still in its infancy. Herein, a rhodium-catalyzed enantioselective formal [4+1] cyclization of benzyl alcohols and benzaldimines has been realized by enantioselective difunctionalization of a secondary silane reagent, affording chiral-at-silicon cyclic silyl ethers and sila-isoindolines, respectively. Mechanistic studies reveal a dual role of the rhodium-hydride catalyst. The coupling system proceeds via rhodium-catalyzed enantio-determining dehydrogenative OH silylation of the benzyl alcohol or hydrosilylation of the imine to give an enantioenriched silyl ether or silazane intermediate, respectively. The same rhodium catalyst also enables subsequent intramolecular cyclative C-H silylation directed by the pendent Si-H group. Experimental and DFT studies have been conducted to explore the mechanism of the OH bond silylation of benzyl alcohol, where the Si-O reductive elimination from a Rh(III) hydride intermediate has been established as the enantiodetermining step.

Copper-catalyzed boroacylation of allenes to access tetrasubstituted vinylboronates.

A distinct copper-catalyzed boroacylation of allenes with acyl chlorides and bis(pinacolato)diboron is developed. For aromatic acyl chlorides, 1,2-boroacylation of allenes readily takes place, leading to the formation of tetrasubstituted vinylboronates with exclusive (E)-stereoselectivity. In comparison, the employment of alkyl acyl chlorides as electrophiles alters the selectivity to 2,3-boroacylated products. Additionally, the product can easily undergo Suzuki-Miyaura cross-coupling to afford tetrasubstituted alkene with complete retention of the configuration.

Enantiodivergent Desymmetrization in the Rhodium(III)-Catalyzed Annulation of Sulfoximines with Diazo Compounds.

RhIII - and IrIII -catalyzed asymmetric C-H functionalization reactions of arenes have relied on the employment of chiral RhIII /IrIII cyclopentadienyl catalysts, the introduction of chiral carboxylic acids to achiral Cp*RhX2 catalysts, and the integration of both strategies. Despite considerable progress, each reaction only provided a specific configuration of the enantioenriched product when using a particular chiral catalyst. Reported in this work is the enantiodivergent coupling of sulfoximines with various diazo compounds by RhIII -catalyzed desymmetrizing annulation. The enantiodivergence was enabled by a judicious choice of achiral carboxylic acids, and the enantioselectivity correlates with the steric bias of the carboxylic acid and the sulfoximine.

Chromosome-level genome assembly provides new insights into Japanese chestnut (Castanea crenata) genomes.

Japanese chestnut (Castanea crenata Sieb. et Zucc) is an economically and ecologically important chestnut species in East Asia. Here, we presented a high-quality chromosome-level reference genome of the Japanese chestnut cultivar 'Tsukuba' by combining Nanopore long reads and Hi-C sequencing. The final assembly has a size of 718.30 Mb and consists of 12 pseudochromosomes ranging from 41.03 to 92.03 Mb, with a BUSCO complete gene percentage of 97.6%. A total of 421.37 Mb repetitive sequences and 46,744 gene models encoding 46,463 proteins were predicted in the genome. Genome evolution analysis showed that Japanese chestnut is closely related to Chinese chestnut and these species shared a common ancestor ~6.5 million years ago. This high-quality Japanese chestnut genome represents an important resource for the chestnut genomics community and will improve our understanding of chestnut biology and evolution.

Ruthenium(ii)-catalyzed intermolecular annulation of alkenyl sulfonamides with alkynes: access to bicyclic sultams.

A ruthenium-catalyzed allylic C(sp3)-H activation strategy has been employed to develop an intermolecular coupling of alkenyl sulfonamides with alkynes. This protocol features the diastereoselective construction of [3.3.0] and [4.3.0] bicyclic sultams in one step.

Enantioselective Copper-Catalyzed Hydroamination of Vinylarenes with Anthranils.

Copper hydride-catalyzed asymmetric hydroamination of olefins with anthranils has been realized in high efficiency and high enantioselectivity, affording enantioenriched secondary arylamines tethered to a benzylic alcohol. The bifunctionality of the product has been employed in diverse derivatization reactions.

Rh(III)-Catalyzed Oxidative Annulation Leading to Substituted Indolizines by Cleavage of C(sp(2))-H/C(sp(3))-H Bonds.

Rhodium(III)-catalyzed oxidative annulation reactions of pyridinium trifluoromethanesulfonate salts with alkynes leading to substituted indolizines by cleavage of C(sp(2))-H/C(sp(3))-H bonds are developed. The starting materials are readily available, and the reactions have a broad substrate scope. This reaction overcomes some drawbacks of the previous indolizine synthetic methods and provides a new efficient route to indolizine derivatives.