Ligand‐Controlled Stereoselective Synthesis of 2‐Deoxy‐β‐C‐glycosides by Cobalt Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(22)

Опубликована: Март 17, 2023

2-Deoxy-β-C-glycosides represent an important class of carbohydrates that are present in many bioactive molecules. However, owing to the lack substituents at C2 position, stereoselective synthesis 2-deoxy-β-C-glycosides is highly challenging. Herein, we report a ligand-controlled C-alkyl glycosylation reaction access 2-deoxy-β-C-alkyl glycosides from readily available glycals and alkyl halides. This method exhibits broad substrate scope excellent diastereoselectivity under very mild conditions. In addition, unprecedented stereodivergent 2-deoxy-C-ribofuranosides achieved using different chiral bisoxazoline ligands. Mechanistic studies suggest hydrometallation glycal with bisoxazoline-ligated Co-H species may be turnover-limiting stereodetermining step this transformation.

Язык: Английский

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Nickel-Catalyzed Migratory Cross-Coupling Reactions: New Opportunities for Selective C–H Functionalization

Accounts of Chemical Research, Год журнала: 2023, Номер 56(23), С. 3475 - 3491

Опубликована: Ноя. 16, 2023

ConspectusMigratory cross-coupling via metal migration is a process of significant academic and industrial interest. It provides an attractive alternative for the selective installation functional group at remote C-H positions from simple precursors, thus enabling direct synthesis challenging structures not accessible with traditional cross-coupling. In particular, merger 1,n-Ni/H shift nickel, Ni-catalyzed migratory functionalization precursors has undergone particularly intense development emerged as valuable field research in past few years. This Account will outline recent progress made this arena terms migration-functionalization modes, diverse functionalizations, strategies regio- stereocontrol. Mechanistic studies synthetic applications are also discussed.In detail, we systematically categorize our work into two parts based on modes. first part, platform created sp3 alkenes or alkyl halides iterative 1,2-Ni/H shift-selective The key reactive Ni(II)H species chain-walking could be generated situ either polarity-reversed fashion relying stoichiometric reductants (X-Ni(II)-H) redox-neutral participation nucleophilic coupling partners (FG-Ni(II)-H). One advantage associated NiH system use relatively stable, abundant, safe olefin surrogates instead sensitive organometallics required reactions. Another that including carbonation more amination thiolation smoothly achieved suitable electrophiles their precursors. Finally, to address multifaceted selectivity reactivity issues asymmetric reactions, have developed feasible ligand relay catalytic strategy. dynamic exchange process, one promotes rapid while other highly stereoselective coupling. innovative strategy overcomes formidable challenge stemming difficulty designing single efficiently promote both steps second new sp2 1,4-Ni/H been reported. Starting readily available aryl vinyl partners, situ-generated aryl- vinylnickel(II) undergo reversible along backbone, subsequent various would allow access 1,4-migratory products. success was discovery appropriate A vinyl-to-aryl successfully enables modular ipso/ortho difunctionalization aryl-to-vinyl functionalized trisubstituted alkenes.We hope inspire broad interest future We strongly believe continued efforts fascinating overcome many remaining challenges, cutting-edge ligand/catalyst design enhance selectivity, conceptually modes additional transformations, in-depth mechanistic rational reaction design.

Язык: Английский

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Asymmetric alkyl-alkyl cross-coupling enabled by earth-abundant metal-catalyzed hydroalkylations of olefins

Chem Catalysis, Год журнала: 2023, Номер 3(4), С. 100508 - 100508

Опубликована: Янв. 30, 2023

Язык: Английский

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Divergent Access to Chiral C2- and C3-Alkylated Pyrrolidines by Catalyst-Tuned Regio- and Enantioselective C(sp³)–C(sp³) Coupling

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(28), С. 15456 - 15464

Опубликована: Июнь 12, 2023

Novel-substituted pyrrolidine derivatives are widely used in drugs and bioactive molecules. The efficient synthesis of these valuable skeletons, especially enantiopure derivatives, is still recognized as a key bottleneck to overcome chemical synthesis. Herein, we report highly catalyst-tuned regio- enantioselective hydroalkylation reaction for the divergent chiral C2- C3-alkylated pyrrolidines through desymmetrization readily available 3-pyrrolines. catalytic system consists CoBr2 with modified bisoxazoline (BOX) ligand, which can achieve asymmetric C(sp3)-C(sp3) coupling via distal stereocontrol, providing series high efficiency. Moreover, nickel allows synthesize C2-alkylated tandem alkene isomerization/hydroalkylation reaction. This method uses catalysts, BOX ligands, reagents, delivering enantioenriched 2-/3-alkyl substituted excellent enantioselectivity (up 97% ee). We also demonstrate compatibility this transformation complex substrates derived from molecules good efficiency, offers distinct entry more functionalized N-heterocycles.

Язык: Английский

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Cobalt‐Catalyzed Facial‐Selective Hydroalkylation of Cyclopropenes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(30)

Опубликована: Май 31, 2023

Abstract Cyclopropene hydrofunctionalization has been a promising strategy for accessing multi‐substituted cyclopropanes; however, cyclopropene hydroalkylation remains underdeveloped. Herein, we report low‐valent CoH‐catalyzed facial‐selective to access cyclopropanes. This reaction exhibits broad substrate scope of alkyl halides and cyclopropenes tolerates many functional groups. Moderate‐to‐good facial‐selectivity is obtained without any directing Mechanism studies provide evidence that radicals are generated from irreversible CoH insertion responsible the facial‐selectivity. Our preliminary exploration demonstrates asymmetric can be realized conspicuous auxiliary

Язык: Английский

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