Tetracoordinate Boron Intermediates Enable Unconventional Transformations

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(9), P. 2298 - 2312

Published: April 14, 2021

ConspectusOrganoboron compounds are a class of multifunctional reagents for the construction carbon–carbon and carbon–heteroatom bonds in modern synthetic chemistry. The transformations organoboron usually carried out through tetracoordinate boron intermediates mainly include additions to unsaturated bonds, rearrangement reactions, transmetalation so on. Although great progress has been achieved improving intermediates, there still shortcomings, such as sparse activation modes, paucity reaction strategies difficulties stereoselective control. In this Account, we discuss our recent advances development unconventional based on design including following three topics: (1) C–B bonds; (2) C–C (3) application chiral boron.The new build is interest chemists. We have developed tandem reactions involving multiple selective borylations alkynes synthesis stable boron, domino-borylation-protodeboronation (DBP) strategy alkynes, highly regio-, stereo-, chemoselective Cu-catalyzed diborylation β-CF3-1,3-enynes cascade B–Cl/C–B cross-metathesis C–H bond borylation triarylboranes. also novel form because formation an enduring theme organic disclosed long distance or migration coupling partners 1,4-migrations nitrile oxide nitrilium migrations isocyanide intermediate, palladium-catalyzed Suzuki–Miyaura thioureas thioamides, copper-catalyzed atroposelective Michael-type addition, Catellani reaction. Moreover, terms control found that tricoordinate complex could activate water with Brønsted acidity, which successfully applied high enantioselectivity asymmetric catalytic reduction challenging indoles.This Account summarizes efforts using not only precise wide range diverse but acid indoles.

Language: Английский

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Stereodivergent Synthesis of Enantioenriched γ‐Butyrolactones Bearing Two Vicinal Stereocenters Enabled by Synergistic Copper and Iridium Catalysis

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(47), P. 24930 - 24940

Published: Oct. 11, 2021

By virtue of a fundamentally new reaction model azomethine ylide serving as two-atom synthon, we present the first example stereodivergent preparation γ-butyrolactones via synergistic Cu/Ir-catalyzed asymmetric cascade allylation/lactonization, and all four stereoisomers bearing two vicinal stereocenters are accessible with excellent diastereoselective enantioselective control. The chiral IrIII -π-allyl intermediate was separated characterized to understand origin regio- stereoselectivity initial C-C bond formation process. Control experiments shed some light on catalyst/substrate catalyst/catalyst interactions in this dual catalytic system rationalize related kinetic/dynamic kinetic resolution process different catalyst combinations. enantioenriched γ-butyrolactone products were converted into an array structurally complex molecules organocatalysts that otherwise inaccessible.

Language: Английский

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Dispersion and Steric Effects on Enantio-/Diastereoselectivities in Synergistic Dual Transition-Metal Catalysis

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(4), P. 1971 - 1985

Published: Jan. 20, 2022

Comprehensive computational studies were carried out to explore the mechanisms of enantioselective Cu/Pd and stereodivergent Cu/Ir dual-catalytic syntheses α,α-disubstituted α-amino acids (α-AAs). A chiral copper azomethine ylide undergoes facile α-allylation with racemic π-allylpalladium species or stereopure π-allyliridium complex stereoconvergently stereodivergently furnish single/double stereocenters, respectively. Stereoselectivity at α-center is controlled by facial selectivity respect prochiral nucleophile. Despite apparently similar transition-state assemblies, models distortion/interaction analyses disclose versatile modes stereoinduction wherein can face-selectively intercept metal−π-allyl intermediates utilizing attractive dispersion interactions and/or sterically caused distortions. Generation β-stereocenter in system relies on a stereospecifically generated allyliridium electronically branched-to-linear selectivity, while dual yields linear monochiral product due steric factors π–π stacking interactions. The demonstrate molecular level how ligand-encoded information transferred α-/β-sites resulting α-AAs mode regio-/stereoselection altered differences transition-metal-stabilized coupling partners. To facilitate stereoselective catalysis, suite analytical tools extract controlling for asymmetric induction demonstrated.

Language: Английский

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Photochemical Organocatalytic Benzylation of Allylic C–H Bonds

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(3), P. 1113 - 1118

Published: Jan. 14, 2022

We report a radical-based organocatalytic method for the direct benzylation of allylic C-H bonds. The process uses nonfunctionalized substrates and readily available benzyl radical precursors is driven by visible light. Crucial was identification dithiophosphoric acid that performs two distinct catalytic roles, sequentially acting as donor formation photoactive electron donor-acceptor (EDA) complexes then hydrogen atom abstractor. By mastering these orthogonal generation paths, organic catalyst enables benzylic radicals, respectively, to govern their selective coupling. protocol also used design three-component process, which increased synthetic potential chemistry.

Language: Английский

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Stereodivergent total synthesis of rocaglaol initiated by synergistic dual-metal-catalyzed asymmetric allylation of benzofuran-3(2H)-one

Chem, Journal Year: 2022, Volume and Issue: 8(7), P. 2011 - 2022

Published: May 2, 2022

Language: Английский

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