Organoboronic Acids Research Articles

Visible-Light-Mediated Aminoquinolate Diarylboron-Catalyzed Metal-Free Hydroxylation of Organoboronic Acids under Air and Room Temperature

An aminoquinolate diarylboron-catalyzed photoredox hydroxylation process has been realized herein. Via aerobic oxidation of organoboronic acid derivatives under air, a variety of functionalized phe...

Pd-Catalyzed Enantioselective Syntheses of Trisubstituted Allenes via Coupling of Propargylic Benzoates with Organoboronic Acids.

Enabled by the newly developed ligand, Ming-Phos, the first example of palladium-catalyzed highly enantioselective coupling of racemic propargylic benzoates with organoboronic acids for chiral allenes synthesis has been developed. Excellent asymmetric induction has been achieved with a decent substrate scope. Synthetic potentials for the construction of polycyclic compounds with multiple chiral centers have been demonstrated.

Front Cover Picture: Rhodium‐Catalyzed Asymmetric Conjugate Addition of Organoboronic Acids to Carbonyl‐Activated Alkenyl Azaarenes (Adv. Synth. Catal. 15/2020)

Front Cover Picture: Rhodium‐Catalyzed Asymmetric Conjugate Addition of Organoboronic Acids to Carbonyl‐Activated Alkenyl Azaarenes (Adv. Synth. Catal. 15/2020)

Rhodium‐Catalyzed Asymmetric Conjugate Addition of Organoboronic Acids to Carbonyl‐Activated Alkenyl Azaarenes

AbstractThe enantioselective synthesis of chiral azaarenes by rhodium‐catalyzed asymmetric conjugate addition of organoboronic acids to carbonyl‐activated alkenyl azaarenes was reported. Diverse chiral azaarenes were produced in up to 99% yield and with up to 99% ee (>60 examples). Catalytic asymmetric syntheses of dexchlorpheniramine and dexbrompheniramine were realized by using the developed method.magnified image

Organoboron-Functionalization Enables the Hierarchical Assembly of Giant Polyoxometalate Nanocapsules.

The aggregation of molecular metal oxides into larger superstructures can bridge the gap between molecular compounds and solid‐state materials. Here, we report that functionalization of polyoxotungstates with organo‐boron substituents leads to giant polyoxometalate‐based nanocapsules with dimensions of up to 4 nm. A “lock and key” mechanism enables the site‐specific anchoring of aromatic organo‐boronic acids to metal‐functionalized Dawson anions [M3P2W15O62]9− (M=TaV or NbV), resulting in unique nanocapsules containing up to twelve POM units. Experimental and theoretical studies provide initial insights into the role of the organo‐boron moieties and the metal‐functionalized POMs for the assembly of the giant aggregates. The study therefore lays the foundations for the design of organo‐POM‐based functional nanostructures.

Rh‐Catalyzed Reaction of Propargylic Alcohols with Aryl Boronic Acids–Switch from β‐OH Elimination to Protodemetalation

Summary of main observation and conclusionIt is known that Rh‐catalyzed reaction of propargylic alcohols with aryl metallic reagents undergoes SN2’‐type reaction affording allenes via a sequential arylmetalation and β‐OH elimination process. Here we report a Rh/Ag‐cocatalyzed reaction of propargylic alcohols with organoboronic acids affording stereo‐defined (E)‐3‐arylallylic alcohols via arylmetalation and protodemetalation with a high regio‐ and stereoselectivity under very mild conditions. The reaction exhibits a good substrate scope and the compatibility with synthetically useful functional groups with no racemization for optically active propargylic alcohols. Such a reaction may also be extended to homopropargylic alcohols with a remarkable regioselectivity and exclusive E‐stereoselectivity.

Palladium‐Catalyzed Coupling of Propargylic Alcohols with Boronic Acids under Ambient Conditions

Summary of main observation and conclusionA highly efficient palladium‐catalyzed direct coupling of propargylic alcohols with organoboronic acids to synthesize tri‐ and tetra‐substituted allenes has been developed under mild reaction conditions. Many useful functional groups are tolerated in this process with high to excellent yields. Preliminary biological studies showed that several tri‐ and tetra‐substituted allenes exhibited potent anti‐diabetic activities.

Catalyst-Controlled Chemodivergent Synthesis of Spirochromans from Diarylideneacetones and Organoboronic Acids

A chemodivergent synthesis of two series of spirochromans depending on the catalytic system was developed. Starting from diarylideneacetones and organoboronic acids, asymmetric rhodium catalysis le...

Nickel-catalyzed regio- and diastereoselective hydroarylative and hydroalkenylative cyclization of 1,6-dienes

An unprecedented nickel-catalyzed hydroarylative and hydroalkenylative cyclization of unsymmetrically substituted 1,6-dienes with organoboronic acid was developed by using MeOH as the hydrogen source and employing commercially available Ni(η2-1,5-cyclooctadiene)2 as the catalyst. A series of biologically interesting cyclic products were afforded in moderate to excellent yields with high regio- and diastereoselectivities.

Manganese-Catalyzed Hydroarylation and Hydroalkenylation of α,β-Unsaturated Amides with Organoboronic Acids

Manganese-Catalyzed Hydroarylation and Hydroalkenylation of <i>α</i>,<i>β</i>-Unsaturated Amides with Organoboronic Acids

Coupling of Trifluoroacetaldehyde N-Triftosylhydrazone with Organoboronic Acids for the Synthesis of gem-Difluoroalkenes.

The synthesis of alkyl gem-difluoroalkenes remains a difficult task in organic synthesis. Here, we report a general and efficient approach for tackling this problem by gem-difluoroolefination of trifluoroacetaldehyde N-triftosylhydrazone with organoboronic acids. This protocol is operationally simple, free of transition metals, and suitable for a broad range of organoboronic acids. Moreover, the utility of the products was demonstrated by further conversion of the gem-difluorovinyl group.

Phenoxy‐Dialkoxy Borates as a New Class of Readily Prepared Preactivated Reagents for Base‐Free Cross‐Coupling

One of the most useful chemical transformations of organoboronic acids is the Suzuki–Miyaura cross‐coupling reaction. Although it has vast application, it possesses some limitations: boronic acids can be difficult to quantify accurately due to their tendency to form oligomeric anhydrides and they must be activated under basic conditions. To address these problems, a new class of boronic acid derivatives is described. Phenoxy‐dialkoxy borates are prepared under mild conditions and show good solubility in common organic solvents. These adducts can be used in base‐free metal‐catalysed cross‐coupling reactions, including orthogonal reactions with MIDA boronates and trifluoroborates.

Copper-Catalyzed Regio- and Stereoselective 1,1-Dicarbofunctionalization of Terminal Alkynes

The copper-catalyzed highly regio- and stereoselective 1,1-dicarbofunctionalization of terminal alkynes is realized for the first time. Using a removable, bidentate 8-aminoquinoline auxiliary, the three-component, selective 1,1-arylalkylation of alkynes with α-haloacetamides and organoboronic acids by the addition of both alkyl and aryl groups to the terminal carbon of alkynes was achieved. Mechanistic investigations suggest that the reaction likely proceeds via the copper-catalyzed cross-coupling of terminal alkynes with α-haloamides, rearrangement, transmetalation, syn-carbocupration, and protonolysis.

Rhodium-Catalyzed Expeditious Synthesis of Indenes from Propargyl Alcohols and Organoboronic Acids by Selective 1,4-Rhodium Migration over β-Oxygen Elimination

An expeditious synthetic route to 1,1-disubstituted indenes from propargyl alcohols and organoboronic acids was developed under rhodium catalysis, and selective 1,4-rhodium migration over β-oxygen elimination was involved as the key step. DPEphos was found to be crucial to promote the transformation, and density functional theory (DFT) calculations indicated that DPEPhos can lower the relative energy of the key intermediate on the 1,4-migration path, leading to the unusual selectivity.

Direct synthesis of N-substituted 1,3-oxazolidines via a hetero-domino Petasis borono-Mannich reaction of 1,2-amino alcohols, formaldehyde, and organoboronic acids

A simple and convenient approach to the synthesis of N-substituted 1,3-oxazolidines via a hetero-domino Petasis borono-Mannich reaction of 1,2-amino alcohols, formaldehyde, and organoboronic acids has been reported. The transformation provides an effective and complementary pathway toward 1,3-oxazolidine derivatives.

An efficient Pd(II)-(2-aminonicotinaldehyde) complex as complementary catalyst for the Suzuki-Miyaura coupling in water

An efficient new Pd(II)-(2-aminonicotinaldehyde)-catalyzed Suzuki-Miyaura coupling of the aryl halides (Br, Cl and I) and organoboronic acids at moderate temperature in water is described. Low catalyst loading, easy accessibility, being an air-stable catalyst, functional group compatibility, and water as the reaction medium are some of the key features of this synthetic method. This protocol is also applicable for gram scale.

Bio-inspired iron-catalyzed oxidation of alkylarenes enables late-stage oxidation of complex methylarenes to arylaldehydes

It is a long-standing challenge to achieve efficient and highly selective aerobic oxidation of methylarenes to benzaldehydes, owing to overoxidation problem stemming from the oxidizability of benzaldehyde far higher than the toluene under usual aerobic conditions. Herein we report a bio-inspired iron-catalyzed polymethylhydrosiloxane-promoted aerobic oxidation of methylarenes to benzaldehydes with high yields and selectivities. Notably, this method can tolerate oxidation-labile and reactive boronic acid group, which is normally required to be transformed immediately after its introduction, and represents a significant advance in the area of the chemistry of organoboronic acids, including the ability to incorporate both aldehyde and ketone functionalities into unprotected arylboronic acids, a class that can be difficult to access by current means. The robustness of this protocol is demonstrated on the late-stage oxidation of complex bioactive molecules, including dehydroabietic acid, Gemfibrozil, Tocopherol nicotinate, a complex polyol structure, and structurally complex arylboronic acids.

Catalytic Activation of Cis-Vicinal Diols by Boronic Acids: Site-Selective Acylation of Carbohydrates.

Site-selective acylation of unprotected carbohydrates by using stable, storable, and easily handled imidazole-containing organoboronic acid catalysts is described. This catalytic process with low catalyst loading enables the introduction of a wide variety of acyl functional groups into the equatorial position of cis-vicinal diols in unprotected hexapyranosides with excellent site selectivity. This is the first example that uses a Lewis base-containing boronic acid to enhance the nucleophilicity of hydroxy groups.

Chiral Bidentate Boryl Ligand Enabled Iridium-Catalyzed Asymmetric C(sp2)-H Borylation of Diarylmethylamines.

Optically active organoboronic acids and their derivatives are an important family of target compounds in organic chemistry, catalysis, and medicinal chemistry. Yet there are rare asymmetric catalytic examples reported for the synthesis of these compounds via atom and step economic ways. Herein, we report a chelate-directed iridium-catalyzed asymmetric C(sp2)-H borylation of aromatic C-H bonds directed by free amine groups. The success of these transformations relies on a novel family of chiral bidentate boryl ligands (L).They can be synthesized straightforwardly in three steps starting from readily available ( S, S)-1,2-diphenyl-1,2-ethanediamie (( S, S)-DPEN). The Ir-catalyzed C(sp2)-H borylation comprises two parts. The first part is desymmetrization of prochiral diarylmethylamines. In the presence ofL3/Ir, a vast array of corresponding borylated products were obtained with high regioselectivity and good to excellent enantioselectivities (26 examples, up to 96% ee). The second part, kinetic resolution of racemic diarylmethylamines, was also conducted. Good selectivity values (up to 68%, 11 examples) were obtained whenL8 was used. We also demonstrated the synthetic utility of the current method on gram-scale reaction for several transformations. The C-B bonds of borylatedproducts could be converted to a variety of functionalities including C-O, C-C, C-C, C-Br, and C-Pbonds. Finally, we performed DFT calculations of desymmetrization to understand its reaction pathways.

Visible-light-induced deboronative alkylarylation of acrylamides with organoboronic acids.

A visible-light-induced deboronative alkylarylation of acrylamides with organoboronic acids was developed. In this transformation, boronic acids could be activated by the organic photocatalyst of eosin Y, generating alky free radicals in high efficiency. A broad range of substrate scope was examined and a number of 3,3-disubstituted oxindoles were synthesized in high yields.