Stereoselective Synthesis of Cyclobutanes by Contraction of Pyrrolidines

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(45), С. 18864 - 18870

Опубликована: Ноя. 8, 2021

Here we report a contractive synthesis of multisubstituted cyclobutanes containing multiple stereocenters from readily accessible pyrrolidines using iodonitrene chemistry. Mediated by nitrogen extrusion process, the stereospecific involves radical pathway. Unprecedented unsymmetrical spirocyclobutanes were prepared successfully, and concise, formal cytotoxic natural product piperarborenine B is reported.

Язык: Английский

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Reactivity of oximes for diverse methodologies and synthetic applications

Nature Synthesis, Год журнала: 2022, Номер 1(1), С. 24 - 36

Опубликована: Янв. 12, 2022

Язык: Английский

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Enantioselective Nickel-Catalyzed Reductive Aryl/Alkenyl–Cyano Cyclization Coupling to All-Carbon Quaternary Stereocenters

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(11), С. 4776 - 4782

Опубликована: Март 9, 2022

An enantioselective nickel-catalyzed intramolecular reductive cross-coupling of C(sp2) electrophiles and cyano groups is reported. Enantioenriched CN-containing all-carbon quaternary stereocenters are assembled by desymmetrizing cyclization aryl/alkenyl halide-tethered malononitriles. The use an organic reductant, (EtO)2MeSiH, crucial to the enantioselectivity reactivity. Applications method demonstrated through synthesis bioactive molecules their cyanated analogues total natural product diomuscinone. This study exhibits potential coupling strategies access structurally rigid synthetically versatile from readily available starting materials.

Язык: Английский

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Regio-controllable [2+2] benzannulation with two adjacent C(sp ³ )–H bonds

Science, Год журнала: 2023, Номер 380(6645), С. 639 - 644

Опубликована: Май 11, 2023

Regiocontrol in traditional cycloaddition reactions between unsaturated carbon compounds is often challenging. The increasing focus modern medicinal chemistry on benzocyclobutene (BCB) scaffolds indicates the need for alternative, more selective routes to diverse rigid carbocycles rich C(sp

Язык: Английский

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Asymmetric imino-acylation of alkenes enabled by HAT-photo/nickel cocatalysis

Chemical Science, Год журнала: 2023, Номер 14(23), С. 6449 - 6456

Опубликована: Янв. 1, 2023

By merging nickel-mediated facially selective aza-Heck cyclization and radical acyl C-H activation promoted by tetrabutylammonium decatungstate (TBADT) as a hydrogen atom transfer (HAT) photocatalyst, we accomplish an asymmetric imino-acylation of oxime ester-tethered alkenes with readily available aldehydes the source, enabling synthesis highly enantioenriched pyrrolines bearing acyl-substituted stereogenic center under mild conditions. Preliminary mechanistic studies support Ni(i)/Ni(ii)/Ni(iii) catalytic sequence involving intramolecular migratory insertion tethered olefinic unit into Ni(iii)-N bond enantiodiscriminating step.

Язык: Английский

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Pd-Catalyzed Asymmetric Aza-Heck Cyclization/Sonogashira Reaction of Alkene-Tethered Oxime Esters and Alkynes

ACS Catalysis, Год журнала: 2024, Номер 14(7), С. 5305 - 5313

Опубликована: Март 26, 2024

Over the past few decades, Narasaka–Heck-type difunctionalization of tethered alkenes has emerged as a powerful strategy to produce heterocyclic scaffolds. However, asymmetric synthesis rarely been explored. Herein, we report robust palladium-catalyzed enantioselective Narasaka–Heck cyclization–Sonogashira reaction alkene-tethered oxime esters and terminal alkynes. By employing new Ming-Phos ligand, obtain high yields pyrrolines with quaternary stereocenter enantioselectivities under mild conditions. Density functional theory (DFT) study reveals weak interaction between aromatic ring substrate fragment naphthyl group in which probably accounts for stereoselectivity.

Язык: Английский

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Photoredox/Iron Dual-Catalyzed Insertion of Acyl Nitrenes into C–H Bonds

Organic Letters, Год журнала: 2022, Номер 24(23), С. 4114 - 4118

Опубликована: Июнь 6, 2022

In this work, the use of N-acyloxybenzamides as efficient acyl nitrene precursors under photoredox/iron dual catalysis is reported. The resulting nitrenes could be captured by various types C-H bonds and S- or P-containing molecules. Mechanism investigations suggested that formation from N-acyloxybenzamide occurs a photoredox process, it believed in redox process oxidative N-H bond cleavage prior to reductive N-O N-acyloxybenzamide.

Язык: Английский

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Synthesis of spirooxindolesviaformal acetylene insertion into a common palladacycle intermediate

Chemical Science, Год журнала: 2023, Номер 14(21), С. 5650 - 5655

Опубликована: Янв. 1, 2023

A palladium-catalyzed spirocyclization reaction is reported, which proposed to arise via insertion of an oxabicycle into a palladacycle, formed from carbocyclization and C-H functionalization sequence. Mechanistic studies suggest the diastereoselective post-catalytic retro-Diels-Alder step furnishes alkene, wherein oxibicycle has served as acetylene surrogate. Aryl iodides carbamoyl chlorides were compatible starting materials under same conditions, enabling convergent complementary synthesis spirooxindoles, well other azacycles. These spirooxindoles allowed further transformations that previously unaccessible.

Язык: Английский

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A Cascade C(sp³)−H Annulation Involving C(alkyl),C(alkyl)‐Palladacycle Intermediates

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(45)

Опубликована: Июль 25, 2024

Abstract C−H bond functionalization involving C , ‐palladacycle intermediates provides a unique platform for developing novel reactions. However, the vast majority of studies have been limited to transformations (aryl), ‐palladacycles. In sharp contrast, catalytic reactions (alkyl), (alkyl)‐palladacycles rarely reported. Herein, we disclose an unprecedented cascade C(sp 3 )−H annulation (alkyl)‐palladacycles. this protocol, alkene‐tethered cycloalkenyl bromides undergo intramolecular Heck/C(sp activation generate (alkyl)‐palladacycles, which can be captured by α ‐bromoacrylic acids afford tricyclic fused pyridinediones. addition, strategy also applied indole‐tethered construct pentacyclic pyridinediones via suquential Heck dearomatization/C(sp activation/decarboxylative cyclization. Notably, removal in reaction build interesting skeleton containing four‐membered ring. Preliminary mechanistic experiments indicate that five‐membered serve as key intermediates. Meanwhile, density functional theory (DFT) calculations provided insights into pathway.

Язык: Английский

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Complex Polyheterocycles and the Stereochemical Reassignment of Pileamartine A via Aza-Heck Triggered Aryl C–H Functionalization Cascades

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(38), С. 15593 - 15598

Опубликована: Сен. 21, 2021

Structurally complex benzo- and spiro-fused N-polyheterocycles can be accessed via intramolecular Pd(0)-catalyzed alkene 1,2-aminoarylation reactions. The method uses N-(pentafluorobenzoyloxy)carbamates as the initiating motif, this allows aza-Heck-type amino-palladation in advance of C–H palladation aromatic component. chemistry is showcased first total synthesis alkaloid (+)-pileamartine A, which has resulted reassignment its absolute stereochemistry.

Язык: Английский

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