Radical 1,2-Boron Shift-Enabled Synthesis of β-Thioalkylboronic Esters from β-Boryl NHPI Esters.

A novel protocol for synthesizing β-thioalkylboronic esters via decarboxylative functionalization of β-boronic acid-derived -hydroxyphthalimide (NHPI) esters is reported. This transformation proceeds under mild conditions with a broad substrate scope and facilitates versatile product derivatization. Mechanistic investigations confirm a radical-mediated 1,2-boron migration pathway.

Zr-Catalyzed Assembly of 1,1,1-Triborylalkanes from Alkenes and HBpin.

Multiboronated compounds play more and more significant roles in the chemical community, and 1,1,1-triborylalkanes have emerged as versatile building blocks in organic synthesis. However, efficient strategies for the assembly of such compounds are very rare. A general and atom-economical synthesis of 1,1,1-triborylalkanes from various alkenes with pinacolborane (HBpin) is reported for the first time.

Diastereoselective radical cascade cyclization to access indole-fused diazepine derivatives.

The synthesis of polycyclic indoles is significant in organic chemistry, due to such heterocyclic frameworks being present in numerous bioactive pharmaceuticals and natural alkaloids. Herein, we provide an efficient radical cascade cyclization strategy to generate indole-fused diazepine derivatives using phosphoryl or sulfonyl radicals with -(2-(1-indol-1-yl)phenyl)--methylmethacrylamides. The merits of this synthesis are attributed to its accessible starting materials, broad substrate compatibility and excellent diastereoselectivity.

Bis(pinacolato)Diboron-Enabled Nickel-Catalyzed Regio- and Enantioselective Reductive [3 + 2] Annulation of β-Bromoenones with Alkynes.

Chiral five-membered cyclic tertiary alcohols are important structural motifs in functional materials, pharmaceuticals, and bioactive molecules. Hence, developing efficient methodologies for synthesizing compounds featuring these privileged scaffolds represents a crucial pursuit within synthetic chemistry. Herein, we present a regio- and enantioselective Ni-catalyzed strategy for the reductive [3 + 2] annulation of β-bromoenones with alkynes, providing convenient access to chiral five-membered cyclic tertiary alcohols with high levels of regio-, and enantioselectivity via axial chirality transfer to central chirality.

Difluorocarbene-Enabled Dehydration of Primary Amides To Access Nitriles.

A cost-effective and environmentally friendly method for the direct conversion of primary amides to nitriles was developed using commercially available non-toxic ethyl bromodifluoroacetate as a difluorocarbene precursor under metal-free and ligand-free conditions. The reaction features high yields and tolerates various sensitive moieties, including alkyl, alkenyl, ether, sulfone, sulfoxide, heteroaryl, chloro, bromo, iodo, hydroxyl, nitro, and cyano groups, and late-stage modification of complex molecules is also feasible. Moreover, the present method is effective on large scales, showing potential for industrial application.

Cobalt-Catalyzed Remote Site-Selective Hydroboration of Unactivated Alkenes via Chain-Walking Strategy.

An expedient synthesis of α-aminoboronic acid derivatives via cobalt-catalyzed remote site-selective hydroboration of unactivated alkenes is described herein. The strategy is characterized by its simplicity, site-selectivity, and wide substrate scope, as both terminal and internal alkenes could undergo the reaction smoothly, affording the corresponding products in good yields. According to the mechanism, Co-H is generated from Co(acac) in the presence of HBpin, which starts the chain-walking strategy via a series of alkene insertion and β-H elimination process.

Photoinduced Assembly of Diverse Homoallylic Boronates from -Diborons.

In comparison to alkyl monoboron or 1,2-diboron, which can generate alkyl radicals via tetracoordinate boron species under photocatalytic conditions, the participation of -diborons as substrates in such reactions remains to be developed. Herein, we report a method utilizing -diborons as starting materials to generate α-boryl radicals, which then react with various olefins, successfully and efficiently constructing a diverse range of high-value homoallylic boronates; meanwhile, the -difluorohomoallylic skeletons could also be smoothly obtained. This transformation demonstrates broad substrate scope and excellent tolerance toward functional groups, enhancing the utility of -diboron as precursors for C-C bond construction and the production of valuable products.

Synthesis of Polysubstituted Aromatics via the Pd(II)-Initiated Borono-Catellani Reaction.

Herein, we report a novel palladium(II)-initiated borono-Catellani reaction that utilizes widely accessible aryl boronic acids that serve as both the reaction-initiating and -terminating substrates for the first time. The borono-Catellani reaction was facilitated by cooperative catalysis between Pd(OAc) and NBE, with air serving as the oxidizing agent, opening new venues for developing novel Catellani-type reactions. Importantly, this method is compatible with a wide range of substrates, including naphthaleneboronic acid, phenylboric acid derivatives, alkyl iodides, and aryl iodides, under these environmentally friendly and mild reaction conditions, thereby demonstrating versatile functional group compatibility for the synthesis of valuable polysubstituted aromatics.

Synthesis of Polysubstituted Benzo[][1,5]naphthyridine via Mn(III)-Mediated Domino Cascade Reactions of Cyclopropanols and 2-(2-Isocyanophenyl)acetonitriles.

Domino cascade reactions, which can construct multiple bonds in one pot, are efficient methods to synthesize N-heterocycles and other useful skeletons. Herein, we report an expedient synthesis of polysubstituted benzo[][1,5]naphthyridine via Mn(III)-mediated C-C bond cleavage of cyclopropanols. These reactions were initiated by addition of β-carbonyl radicals, generated from cyclopropyl alcohols in the presence of Mn(III), to 2-(2-isocyanophenyl)acetonitriles to give quinolin-3-amines, which went through intramolecular cyclizations and dehydrogenation to give the final products.

Enantioselective construction of C-B axially chiral alkenylborons by nickel-catalyzed radical relayed reductive coupling.

The catalytic asymmetric synthesis of axially chiral alkenes remains a daunting challenge due to the lower rotational barrier, especially for longer stereogenic axis (e.g. C-B axis).

Photogeneration of β-Borylsilyl Radical via Decarboxylation of -Hydroxyphthalimide Esters.

-borylsilylalkanes are versatile intermediates in organic synthesis, and the traditional synthesis methods have mainly focused on metal reagents, the insertion reactions of diazo compounds, and hydrosilylation/hydroborylation reactions of unsaturated bonds. Herein, a novel, efficient -borylsilylalkanes synthesis via a radical approach is reported. This method introduced a β--borylsilyl NHPI ester as the precursor of the β-borylsilyl radical that, coupling with radical acceptors under photo conditions, and the corresponding -borylsilylalkanes bearing unsaturated bonds, facilitate subsequent transformations.

Interception of Alkynyl Tetracoordinate Borons with Sulfur Electrophiles beyond the Zweifel Pathway.

Zweifel reaction is a powerful strategy to construct olefins from alkenyl tetracoordinate borons in organoboron chemistry, however, it usually only involves one functional group migration and then undergoes an elimination process affording alkenes or alkynes exclusively. Herein, we disclose several intriguing interception of alkynyl tetracoordinate borons with sulfur electrophiles. Wherein, the substituted benzothiophenes are accessed by consecutive 1,2-migrations and intramolecular electrophilic substitution, meanwhile, the challenging and elusive five/four-membered boracycles are easily assembled, and an approach to alkenyl sulfides with good stereoselectivity was developed as well.

Rh(III)-Catalyzed Regioselective Alkyne Insertion in the Context of C-H Activation and Lactonization Reactions: Synthesis of Fused 1,2-Oxaphospholenes.

Herein, we report an expedient synthesis of fused phosphorus-containing heterocycles via Rh-catalyzed cascade C-H activation, alkyne insertion, and lactonization reactions. The substrate scope and the group tolerance are good, as various substituted benzoic acids, -methoxybenzamides, and 2-phenylindoles could go through the reactions smoothly to afford the corresponding products in moderate to high yields. Additionally, excellent regioselectivities are shown in the alkyne insertion with the assistance of an electron-withdrawing phosphonate group.

Photo-induced decarboxylative C-S bond formation to access sterically hindered unsymmetric S-alkyl thiosulfonates and SS-alkyl thiosulfonates.

Due to the high reactivity and versatility of benzenesulfonothioates, significant advancements have been made in constructing C-S bonds. However, there are certain limitations in the synthesis of S-thiosulfonates and SS-thiosulfonates, especially when dealing with substantial steric hindrance, which poses a significant challenge. Herein, we present an innovative approach for assembling unsymmetric S-thiosulfonates and unsymmetric SS-thiosulfonates through the integration of dual copper/photoredox catalysis.

Chemo-, regio- and stereoselective access to polysubstituted 1,3-dienes via Nickel-catalyzed four-component reactions.

1,2-Difunctionalization of alkynes offers a straightforward approach to access polysubstituted alkenes. However, simultaneous multi-component cascade transformations including difunctionalization of two alkynes with both syn- and anti-selectivity in one catalyst system is undeveloped and proves to be a significant challenge. Herein, we report a Nickel-catalyzed four-component reaction to access polysubstituted 1,3-dienes using two terminal alkynes, aryl boroxines, and perfluoroalkyl iodides, wherein the reaction forms three new C-C bonds in a single vessel and serve as a modular strategy to access polysubstituted 1,3-dienes with excellent chemoselectivity, good regioselectivity and exclusive stereoselectivity.

Difluorocarbene-induced [1,2]- and [2,3]-Stevens rearrangement of tertiary amines.

The [1,2]- and [2,3]-Stevens rearrangements are one of the most fascinating chemical bond reorganization strategies in organic chemistry, and they have been demonstrated in a wide range of applications, representing a fundamental reaction tactic for the synthesis of nitrogen compounds in chemical community. However, their applicabilities are limited by the scarcity of efficient, general, and straightforward methods for generating ammonium ylides. Herein, we report a general difluorocarbene-induced tertiary amine-involved [1,2]- and [2,3]-Stevens rearrangements stemmed from in situ generated difluoromethyl ammonium ylides, which allows for the rearrangements of versatile tertiary amines bearing either allyl, benzyl, or propargyl groups, resulting in the corresponding products in one reaction under the same reaction conditions with a general way.

Enantioselective copper-catalyzed B-H bond insertion reaction of α-diazo phosphonates to access chiral α-boryl phosphonates.

Chiral phosphorus-containing compounds find applications across various fields, including asymmetric catalysis, medicinal chemistry, and materials science. Despite the abundance of reported highly enantioselective methods for synthesizing various chiral phosphorus compounds, the enantioselective synthesis of α-boryl phosphorus compounds still remains an unknown territory. Here, we report a method for the construction of chiral α-boryl phosphates by asymmetric B-H insertion reaction using α-diazo phosphates as carbene precursors, cheap and readily available copper salt as the catalyst and chiral oxazoline as the ligand.

Difluorocarbene Enables Access to 2,2-Difluorohydrobenzofurans and 2-Fluorobenzofurans from -Vinylphenols.

2-Fluorobenzofurans are the backbone structures of many drug molecules and have many potential therapeutic bioactivities. Despite the potential applications in medicinal chemistry, practical and efficient synthetic methods for the construction of 2-fluorobenzofuran are very limited. Herein, we report an efficient and general method for the construction of 2-fluorobenzofurans.

Copper-catalysed asymmetric hydroboration of alkenes with 1,2-benzazaborines to access chiral naphthalene isosteres.

Bioisosteric replacement has emerged as a clear strategy for drug-structure optimization. Naphthalene is the core element of many chiral pharmaceuticals and drug candidates. However, as a promising isostere of naphthalene, the chiral version of 1,2-benzazaborine has rarely been explored due to the lack of efficient synthetic methods.

1,1-Oxycarbonation of Terminal Alkynes via Sequential Borylation, 1,2-Migration, and Oxidation with Oxone.

Alkynes are readily available and multifunctional synthetic intermediates, but their 1,1-oxofunctionalization remains challenging. Herein, we report a 1,1-oxycarbonation of terminal alkynes to construct ketones through sequential borylation, 1,2-carbon migration, and oxidation with Oxone as the proton source and oxidant. The synthetic potential of this transformation is showcased by the broad functional groups, scale-up synthesis, and diverse product transformations.

Unlocking Diverse π-Bond Enrichment Frameworks by the Synthesis and Conversion of Boronated Phenyldiethynylethylenes.

The π-bond enrichment frameworks not only serve as a crucial building block in organic synthesis but also assume a pivotal role in the fields of materials science, biomedicine, photochemistry, and other related disciplines owing to their distinctive structural characteristics. The incorporation of various substituents into the C═C double bonds of tetrasubstituted alkenes is currently a highly significant research area. However, the synthesis of tetrasubstituted alkenes with diverse substituents on double bonds poses a significant challenge in achieving stereoselectivity.

"Homoleptic" Tetracoordinate Boron Compounds.

"Homoleptic" tetracoordinate boron compounds, in which the central boron atom links to four identical atoms, are a special and important family of boron compounds. During the past decades, they have been extensively employed in inorganic, organic, macromolecular, and materials chemistry. Many of them exhibit a diverse range of outstanding properties, and therefore, the synthesis and application of those compounds have emerged as a hot research topic in modern boron chemistry.

Recent progress in the catalytic enantioselective reactions of 1,1-diborylalkanes.

Organoboron compounds are environmentally benign, have low toxicity and are versatile reagents that are extensively employed in organic synthesis, especially in the realm of asymmetric synthesis. The last several decades have witnessed a tremendous outburst of asymmetric reactions based on various organoboron compounds. Among them, 1,1-diborylalkanes, which contain two boryl groups at the same sp-carbon atom, are regarded as some of the most versatile and powerful reagents for their unique structure and unusual reaction mode in organic synthesis.

N-Heterocycle-Editing to Access Fused-BN-Heterocycles via Ring-Opening/C-H Borylation/Reductive C-B Bond Formation.

Skeletal editing of N-heterocycles has recently received considerable attention, and the introduction of boron atom into heterocycles often results in positive property changes. However, direct enlargement of N-heterocycles through boron atom insertion is rarely reported in the literature. Here, we report a N-heterocyclic editing reaction through the combination boron atom insertion and C-H borylation, accessing the fused-BN-heterocycles.