Synthesis of Skipped Aminodienes by a Ni-Catalyzed Ring-Opening/Cross-Coupling Reaction of Vinylaziridines with Multifunctional Organoboronic Acids

Skipped dienes are of great importance but remain challenging to synthesize because of the presence of a sp hybrid carbon between the two alkenes.Herein,we have developed the first nickel-catalyzed regio-,(E)-stereo-and linear-selective ring-opening/cross-coupling reaction of vinylaziridines with organoboronic acids under mild conditions to construct various skipped aminodienes.The reaction exhibits wide functional-group compatibility,and could be adapted for the introduction of skipped aminodiene functionality into bioactive molecules.

Coupling Reaction of Organoboronic Acids with Chloropyrimidines and Trichlorotriazine

Pd-catalyzed cross-coupling reactions of chloropyrimidines with alkenylboronic acids readily proceed to give the corresponding alkenylpyrimidines in high to excellent yields. The coupling reaction of 2,4-dichloropyrimidine or 2,4,6-trichloropyrimidine with one equivalent of alkenylboronic acid occurred more easily on 4-position than on 2-position, which implied that the reaction is highly regioselective. The reaction is stereospecific since the configu-ration of C=C remained intact. The preliminary study on the cross-coupling reactions of 2,4,6-trichlorotriazine with one equivalent of arylboronic acids showed that the reactions afforded the monosubstituted triazines in moder-ate yields. The effect of steric hindrance of the substitutents on the reactions was found.

Bioengineering functional copolymers. XII. Interaction of boron-containing and PEO branched derivatives of poly(MA-alt-MVE) with HeLa cells

Novel boron-containing bioengineering copoly- mer and its α-hydoxy-ω-methoxy-poly(ethy- lene oxide (PEO) macrobranched derivatives were synthesized by (1) partially amidolysis of poly(maleic anhydride-alt-methyl vinyl ether) w?th ethanolamine ester of diphenylboronic acid and (2) esterification of synthesized B-con- taining copolymers with PEO. They had a com- bination of hydrophilic/hydrophobic linkages, free carboxylic groups, positive charges and an ionized organoboron linkage as antitumor sites, along with an ability to interact with HeLa cells. The structure, composition and properties (cy- totoxicity and antitumor activity) of synthe- sized copolymers were investigated. In vitro cytotoxicity results, obtained by the fluore scence microscopy measurements indicate that unlike the virgin copolymer, boron-containing and PEO macrobranched derivatives exhibit higher antitumor activity. It was found that organoboron copolymer exhibits the most apo- ptotic and necrotic effects against HeLa cells whereas a minor effect relative to cancer cells was observed on L929 Fibroblast cells.

Bioengineering Functional Copolymers. XVII. Interaction of Organoboron Amide-Ester Branched Derivatives of Poly(Acrylic Acid) with Cancer Cells

Novel bioengineering functional organoboron polymers were synthesized by 1) amidolysis of poly(acrcylic acid) (PAA) with 2-aminoethyldiphenyl borinate (2-AEPB), 2) esterification of organoboron PAA polymer (PAA-B) with a-hydroxy-methoxypoly(ethylene oxide) (PEO) as a compatibilizer and 3) conjugation of organoboron PEO branches (PAA-B-PEO) with folic acid (FA) as a targeting agent. Structure and composition of the synthesized polymers were characterized by FTIR-ATR and 1H (13C) NMR spectroscopy, chemical and physical analysis methods. Anti-tumor activity of organoboron functional polymer and its complex with FA (PAA-B-PEO-F) against cancer and normal cells were evaluated by using different biochemical methods such as cytotoxicity, statistical, apoptotic and necrotic cell indexes, double staining and caspase-3 immune staining, light and fluorescence inverted microscope analyses. It was found that citotoxicity and apoptotic/necrotic effects of polymers significantly depend on the structure and composition of studied polymers, and increase the following raw: PAA << PAA-B < PAA-B-PEO < PAA-B-PEO-F. Among them, PAA-B-PEO-F complex at 400 mg mL–1 concentration as a therapeutic drug exhibits minimal toxicity toward the nor-mal cells, but influential for HeLa cancer cells.

SYNTHESES AND CHARACTERIZATION OF CYCLIC ORGANIC BORONATE ESTERS AS FLAME-RETARDANTS

Some organoboron compounds as flame-retardants for fiber materials were prepared.Flame-retarding properties of these compounds determined by the Oxygen-Index Method weregood.These new compounds were characterized by IR,~1H NMR spectrum and elementalanalysis.

Ni-catalyzed highly regio- and stereo-selective diborylative cyclization of 1,6-enynes with diboron reagent

The Ni-catalyzed highly selective diborylative cyclization of 1,6-enynes with diboron reagent has been developed. When pinB-Bdan was used, multiple types of boron-containing functional groups could be installed into organic molecule with great chemoselectivity and regioselectivity though this reaction. Meanwhile, if B_2pai_2 was employed, the asymmetric diborylative cyclization could be well induced by using strategy of dynamic kinetic resolution. Importantly, the above reactions could afford desired product with 100% atomic economy, and could be compatible with different series of substituents. The studies of further transformation well illustrated that different type products could serve diverse synthetic strategy. Notably, the reaction mechanism was intensively studied by density functional theory(DFT) calculations, which could reveal the mechanism of regio- and enantio-selective control.

Sigmatropic rearrangements of B(MIDA)-propargylic alcohols towards the diverse synthesis of α-functionalized organoborons

α-Functionalized organoborons are useful building blocks and key structural elements in functional molecules.Their previous synthesis relied on the famous Matteson reaction or the late-stage borylative modification of alkynes or alkenes.Recently,the synthetic transformation of borylated building blocks offers another useful strategy and is currently actively explored.We report herein that B(MIDA)-propargylic alcohols(BPAs) are a useful type of borylated building blocks.Bearing two complementary functional group handles(alkyne and hydroxyl) in close proximity,the redox-neutral [3,3] and [2,3] sigmatropic rearrangements of BPAs allow the efficient synthesis of several types of α-functionalized boronates,including α,β-unsaturated acylborons,α-S/P-substituted allenylborons,boryl-substituted thiazoles and a borylated α,β-unsaturated hydrazine,some of which are otherwise challenging targets using other synthetic methods.

Enantioselective Alkylation of Aldehydes with Organoborons Enabled by Nickel/N-Heterocyclic Carbene Catalysis

Transition-metal-catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols.However,efficient methods using organoborons as coupling reagents are rare.Herein,we report a highly enantioselective nickel-catalyzed alkylation reaction of aldehydes,using readily available alkylborons as nucleophiles.A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields.The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2-symmetric chiral NHC ligand.This protocol features excellent enantiocontrol,mild conditions,and good functional group compatibility.

Aggregation-Induced Emission(AIE)Active Fluoroboronated Pyridylhydrazinyl Aldehyde Hydrozone Dyes:Synthesis,Crystal Structure and Optical Properties

A new family of fluoroboronated pyridylhydrazinyl aldehyde hydrozone fluorophores named BOPAHs were developed via a simple one-pot two-step reaction from chloro-2-hydrazinylpyridine and aromatic aldehyde derivatives.They were well characterized by NMR,HRMS,and X-ray crystal structures.They exhibit main absorption from 400 nm to 600 nm and emission bands from 500 nm to 700 nm.The absorption/emission bands redshift with increased polarity of solvents indicate a distinct intramolecular charge transfer characteristic,further confirmed by density functional theory(DFT)calculations.These BOPAHs display weak fluorescence in solutions,but they exhibit obvious aggregation-induced emission properties,possibly resulting from weak intermolecular interactions by fixing the molecular conformations in aggregate states.

1,6-Conjugate addition of para-quinone methides using gem-diborylcarbanions: Practical access to gem-diborylalkanes bearing vicinal tertiary/quaternary stereocenters

A novel,efficient and pragmatic method to prepare gem-diboron products with vicinal tertiary/quaternary stereocenters using LiTMP-mediated 1,6-conjugate addition of gem-diborylalkanes to para-quinone methides was described for the first time.The results showed that various gem-diboron products with vicinal tertiary and quaternary stereocenters could be formed within 15 min at ambient temperature.This simple protocol has also been applied for the efficient synthesis of the analogue of Bedaquiline.

Theoretical investigation of photoelectric properties of the four-coordinate organoboron compounds based on diketopyrrolopyrrole derivativ

In order to obtain high efficiency of organic light-emitting diodes and organic solar cells,a series of DPP-based four-coordinate organoboron compounds have been designed for photoelectric functional materials.The effects of electron-donating and-withdrawing substituent on the electronic and optical properties have been investigated by using density functional theory(DFT)and time-dependent DFT(TD-DFT)approaches systematically.It turned out that electron-donating and-withdrawing groups can tune effectively the frontier molecular orbital(FMO)energy level,energy gap,and absorption and fluorescence spectra.The introduction of electron-withdrawing groups for the parent molecule HBDPP(2,5-bis(diphenylboryl)-3,6-bis(pyridin-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione)favors the decrease for the FMO energy(E_(LUMO)and E_(HOMO)),HOMO-LUMO gaps(E_(g)),and the downhill energetic driving force(ΔEL-L),while the electron-donating groups can increase E_(LUMO),E_(HOMO),E_(g),andΔEL-L compared with that of HBDPP,respectively.The absorption and fluorescence spectra of the electron-withdrawing substituted derivatives exhibit bathochromic shifts,while the absorption and fluorescence spectra of the electrondonating substituted derivatives show hypsochromic shifts compared with the parent molecule HBDPP,respectively.Furthermore,the stronger the electron-withdrawing/donating ability of group is,the more significant the effect in the optoelectronic properties.

Organoboron luminophores with extremely strong dual-phase emissions

Developing efficient dual-phase emission emitters upon organoboron luminophores remains a formidable challenge due to the ubiquitous self-absorption and deleterious π-π interactions from aromatic structure.Here, a new family of benzothiazole-enolate-based organoboron luminophores(HN1-4) with effective dual-phase emission was constructed. HN4 showed almost the highest quantum yield(QY) among this type of compound so far. The three-ring-fused rigid skeleton and moderate intramolecular charge transfer(ICT) effect ensured that HN4 could give rise to extremely strong emission in any solution(QY up to 99%). X-ray crystallographic analysis showed that the twisted core structure constructed by the boronic coordination of two penta-fluorobenzene of HN4 was responsible for intense emission in the solid state(QY up to 68%). Besides, HN4 exhibited a unique response to mechanical force accompanied by a reversible change of the QY. We believe that this strategy provides beneficial inspiration and methodology to design materials with high emissive quantum yield that can be used in a variety of luminescent events.

Organoboron chemistry towards controlled and precise polymer synthesis

Organoboron reagents have garnered considerable attention due to their distinct properties. In recent years, boronic acids and boronate esters have been important intermediates for cross-coupling reactions and other functional group construction and are often used to synthesize small organic molecules, drugs, and bioactive substances. In this feature article, we encapsulate the strategy of harnessing the unique properties of organoboron reagents to overcome challenges encountered in conventional polymer synthesis. We delve into the synthesis of boron-containing monomers and polymer materials, unraveling the unique attributes of these newfound polymers while offering innovative insights into their application within recyclable or reprocessable materials. We develop organoboron-based photocatalysts, employing their inner-sphere electron transfer(ISET) mechanisms to initiate controlled radical polymerization. We utilize alkylborane to initiate controlled radical polymerization and further designed B-alkylcatecholboranes to prepare ultra-high molecular weight polymers. Notably, we also propose a liquid-phase synthesis method based on organoboron tags and apply it to the precise synthesis of sequence-controlled conjugated polymers.These advancements open up new frontiers in the realm of polymer science, and the versatility and potential of organoboron reagents in polymer synthesis continue to inspire exciting research endeavors.

Synthesis and Optical Properties of Polyaryl 2-(Pyridin-2-yl)phenol-Based Four-Coordinate Organoboron Complexes

Comprehensive Summary A family of polyaryl 2-(pyridin-2-yl)phenol-based four-coordinate organoboron complexes were prepared in good yields via deconstructive cycloaromatization of indolizines,cyclopropenones,and boric acids.The photoluminescence measurements have revealed that these N,Oπ-conjugated tetracoordinate boron complexes display bright fluorescence,large Stokes shifts,and good quantum yields(Φlum=0.15-0.45).In addition,the DFT calculations were carried out to deepen the understanding of the electronic structures and optoelectronic properties of these structurally unprecedented tetracoordinate boron complexes.

High-Resolution Imaging of Latent Fingerprints through Near-Infrared Organoboron AIEgens

A new class of near-infrared(NIR)fluorescent organoboron AIEgens was successfully developed for latent fingerprints(LFPs)imaging.They exhibit real-time and in situ high-resolution imaging performance at 1-3 levels of LFPs by spraying method.In addition,we systematically elucidate the fingerprint imaging mechanism of these AIEgens.Significantly,the excellent level 3 structural imaging capabilities enable the application of them for analyzing incomplete LFPs and identifying individuals in different scenarios.

Acceptor-acceptor-type Organoboron Conjugated Polymers:Effect of Backbone Configuration on Thermoelectric Performance

The development of n-type polymer thermoelectrics lags far behind that of p-type ones in view of material diversity and performance.New structural insights into the thermoelectric performance are needed for efficient n-type polymer thermoelectric materials.Herein,we developed three acceptor-acceptor type organoboron polymers and investigated the effect of backbone configuration on thermoelectric performance.The three polymers are designed based on double B←N bridged bipyridine(BNBP)unit with monomeric thieno[3,4-c]pyrrole-4,6-dione(TPD),TPD dimer and TPD trimer as the copolymerizing units,respectively.The three polymers show similar low LUMO energy levels but different backbone configuration.Compared with the wavy backbone configuration,the pseudo-straight backbone configuration imparts the polymer with much enhanced crystallinity and electron mobility.As a result,after n-doping,the polymer with pseudo-straight configuration shows much higher electronic conductivity and power factor.We think these findings could serve as important guidelines for molecular design toward efficient n-type polymer thermoelectric materials.

Transition Metal Catalyzed Direct Oxidative Borylation of C--H Bonds

Organoboron is well-developed and broadly utilized organometallic reagents in organic synthesis due to its extraordinary performances in transition-metal catalyzed C-C and C-X bonds construction. Catalytic C--H borylation and further transformations catalyzed by transition metal catalysts in the absence of oxidants were well studied in decades. However, as known, transition metal catalyzed oxidative C-H borylations were not reviewed up to date. In this article the oxidative borylation of C（sp2）-H and C（sp3）-H bonds were summarized and their mechanisms were also accounted.

Ligand-Enabled Ni-Catalyzed Enantioselective Hydroarylation of Styrenes and 1,3-Dienes with Arylboronic Acids

We report an enantioselective hydroarylation reaction of styrenes and 1,3-dienes with arylboronic acids catalyzed by nickel complexes bearing chiral spiro amino phosphine ligands.The reaction serves as an efficient,straightf orward,and mild method for the preparation of enantio enriched 1,1-diarylalkanes,which are important building blocks for the synthesis of many biologically active molecules.This redox neutral reaction uses only catalytic amounts of the reagents and is,therefore,atom economical and environmentally benign.

Photoinduced Transition-Metal-Free Alkynylation of Alkyl Pinacol Boronates

An unprecedented visible-light-induced transitionmetal-free alkynylation of alkyl pinacol boronates has been demonstrated with alkynyl phenylsulfones as the alkynylation reagents and 4CzIPN as the organic photocatalyst.Common sodium methoxide(NaOMe)or sodium hydroxide(NaOH)was used as the Lewis base togeneratephotoactivetetra-coordinatedboron species.Various functional groupswerewell tolerated.The selective monoalkynylation of diboronates was achieved to keep one boryl group in the product for potential further transformations.Radical trapping experiments and electron paramagnetic resonance(EPR)analysis confirmed the generation of alkyl radical intermediate.

Recent advances in room temperature phosphorescence of crystalline boron containing organic compounds

In organic compounds,room temperature phosphorescence(RTP)is a rare,yet highly desirable,property that is important for a wide variety of applications,including tissue imaging,anticounterfeiting technologies,photodynamic therapy,and organic light-emitting devices.While most organic RTP molecules rely on heavy atoms or carbonyl functional groups to accelerate singlet-to-triplet intersystem crossing,in the past few years there have been several reports of RTP induced by boroncontaining functional groups.This minireview covers the recent literature on RTP of crystalline boroorganic compounds and analyzes the connections between molecular structure,intermolecular interactions,and the resulting phosphorescence.