Oxidative Olefination of Anilides with Unactivated Alkenes Catalyzed by an (Electron‐Deficient η5‐Cyclopentadienyl)Rhodium(III) Complex Under Ambient Conditions

The oxidative olefination of sp² C?H bonds of anilides with both activated and unactivated alkenes using an (electron‐deficient η⁵‐cyclopentadienyl)rhodium(III) complex is reported. In contrast to reactions using this electron‐deficient rhodium(III) catalyst, [Cp*RhCl₂]₂ showed no activity against olefination with unactivated alkenes. In addition, the deuterium kinetic isotope effect (DKIE) study revealed that the C?H bond cleavage step is thought to be the turnover‐limiting step.     

Nickel‐Catalyzed Direct Carboxylation of Olefins with CO2: One‐Pot Synthesis of α,β‐Unsaturated Carboxylic Acid Salts

The nickel‐catalyzed direct carboxylation of alkenes with the cheap and abundantly available C₁ building block carbon dioxide (CO₂) in the presence of a base has been achieved. The one‐pot reaction allows for the direct and selective synthesis of a wide range of α,β‐unsaturated carboxylates (TON>100, TOF up to 6 h^?1, TON=turnover number, TOF=turnover frequency). Thus, it is possible, in one step, to synthesize sodium acrylate from ethylene, CO₂, and a sodium salt. Acrylates are industrially important products, the synthesis of which has hitherto required multiple steps.     

Metal triflate catalyzed highly regio- and stereoselective 1,2-bromoazidation of alkenes using NBS and TMSN3 as the bromine and azide sources

Metal triflate catalyzed 1,2-bromoazidation of alkenes was performed using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN₃) as the bromine and azide sources, respectively. Among the metal triflates, Zn(OTf)₂ was found to be the best catalyst. This catalytic process represents a highly regioselective, stereoselective and high yielding method for the synthesis of anti-1,2-bromoazides from a variety of alkenes including α,β-unsaturated carbonyl compounds.     

The PMe3-catalyzed addition of enantiomerically pure (−)-MenthylO(Ph)P(O)H to electron-deficient alkenes: an efficient way for the preparation of P-stereogenic compounds

A variety of P-stereogenic organophosphorus compounds can be readily prepared by stereoretentive addition. The PMe₃-catalyzed addition of optically active (?)MenthylO(Ph)P(O)H compounds to electron deficient alkenes occur stereospecifically, to produce the corresponding P-stereogenic adducts in high yields. By simply removing the volatiles under vacuum, spectroscopically pure products can be obtained. The present method provides a salt-free clean process for the preparation of P-chiral organophosphorus compounds.     

The First Catalytic Synthesis of an Acrylate from CO2 and an Alkene—A Rational Approach

For more than three decades the catalytic synthesis of acrylates from the cheap and abundantly available C₁ building block carbon dioxide and alkenes has been an unsolved problem in catalysis research, both in academia and industry. Herein, we describe a homogeneous catalyst based on nickel that permits the catalytic synthesis of the industrially highly relevant acrylate sodium acrylate from CO₂, ethylene, and a base, as demonstrated, at this stage, by a turnover number of greater than 10 with respect to the metal.     

A facile route for the synthesis of vinyl-substituted 1,3,4-oxadiazoles

An efficient synthesis of vinyl-substituted 1,3,4-oxadiazoles using o-nitrophenyl sulfoxide precursor via syn-elimination reaction using sodium acetate in THF is described. This method is cost effective as it uses cheap o-nitrothiophenol and can be used in the synthesis of vinyl intermediates during synthesis of bioactive compounds, which avoids the use of any toxic metals.     

Photocatalytic Deuterium Atom Transfer Deuteration of Electron-Deficient Alkenes with High Functional Group Tolerance

Due to its mild reaction conditions and unique chemoselectivity, hydrogen atom transfer (HAT) hydrogenation represents an indispensable method for the synthesis of complex molecules. Its analog using deuterium, deuterium atom transfer (DAT) deuteration, is expected to enable access to complex deuterium-labeled compounds. However, DAT deuteration has been scarcely studied for synthetic purposes, and a method that possesses the favorable characteristics of HAT hydrogenations has remained elusive. Herein, we report a protocol for the photocatalytic DAT deuteration of electron-deficient alkenes. In contrast to the previous DAT deuteration, this method tolerates a variety of synthetically useful functional groups including haloarenes. The late-stage deuteration also allows access to deuterated amino acids as well as donepezil-d₂. Thus, this work demonstrates the potential of DAT chemistry to become the alternative method of choice for preparing deuterium-containing molecules.     

Cobalt‐Catalyzed Enantioselective Synthesis of Chiral gem‐Bis(boryl)alkanes

We report an asymmetric synthesis of enantioenriched gem‐bis(boryl)alkanes in an enantioselective diborylation of 1,1‐disubstituted alkenes catalyzed by Co(acac)₂/(R)‐DM‐segphos. A range of activated and unactivated alkenes underwent this asymmetric diborylation in the presence of cyclooctene as a hydrogen acceptor, affording the corresponding gem‐bis(boryl)alkanes with high enantioselectivity. The synthetic utility of these chiral organoboronate compounds was demonstrated through several stereospecific derivatizations and the synthesis of sesquiterpene and sesquiterpenoid natural products.     

A green route for microwave synthesis of sodium tungsten bronzes NaxWO3 (0<x<1)

A green route has been developed for microwave synthesis of sodium tungsten bronzes Na_xWO₃ (0<x<1) from Na₂WO₄, WO₃ and tungsten powder. The hybrid microwave synthesis was carried out in argon atmosphere using CuO powder as the heating medium. Tungsten powder is used as the reducing agent instead of the alkali metal iodides previously used for the microwave synthesis of oxide bronzes. The prepared samples were characterized by powder X-ray diffraction, energy-dispersive X-ray analysis and scanning electron microscopy, and their phase constitutions, crystal structures and morphologies are in consistence with that in the literature. This synthesis method is simple, green and atom economic, and promising for preparation of other oxide bronzes and related compounds.     

Bromofluorination of olefins using BrF3; an efficient route for fluoroalkenes and fluoroamines

A variety of alkenes and α,β-unsaturated carbonyls were reacted with BrF₃ to form vicinal bromofluoro compounds. In most cases, the reactions followed a Markovnikov regioselectivity and anti-addition stereospecifity. They proceeded well even with deactivated olefins in around 70% yield. The bromofluoro compounds served as starting materials for the synthesis of fluoroalkenes and fluoroamines.     

Ready access to organoiodides: Practical hydroiodination and double-iodination of carbon-carbon unsaturated bonds with I2

By using I₂ or I₂/H₃PO₃ system, various alkenes and alkynes were converted to the corresponding alkyl and alkenyl iodides in good yields. In the presence of I₂, alkynes could be di-iodinated using H₂O as the solvent in air at room temperature. This method also features the simple work-up procedure since the pure product could be obtained by extraction. Additionally, for the first time, combining with the non-toxic and cheap phosphonic acid H₃PO₃, alkenes and alkynes were also hydroiodinated successfully, which provides a simple and practical approach for synthesis of organoiodides.     

Organocatalyzed arylalkylation of activated alkenes via decarboxylation of PhI(O2CR)2: efficient synthesis of oxindoles

A novel organocatalyzed arylalkylation of activated alkenes has been developed. This reaction was initiated from the decomposition of PhI(O₂CR)₂ to generate alkyl radical, followed by addition to alkenes. Then the formed radical was trapped by aromatic ring to generate the cyclized products. This method presents an efficient road to synthesis of a variety of oxindoles.     

Synthesis and Application of Poly(diallyldimethylammonium tribromide)as a Novel Polymeric Brominating Agent

In this study, the synthesis and applications of a new supported tribromide reagent based on poly(diallyldimethylammonium chloride) is reported. This supported tribromide is used in α‐bromoacetalization of ketones, bromination of alkenes and regioselective bromination of activated aromatic compounds. This method is mild and no Br₂ and HBr were used. Other advantages of this reagent are stability, high efficiency, simple filtera‐ bility and reusability.     

Sila- and Germacarboxylic Acids: Precursors for the Corresponding Silyl and Germyl Radicals

Silicon-containing compounds are widely used as synthetic building blocks, functional materials, and bioactive reagents. In particular, silyl radicals are important intermediates for the synthesis and transformation of organosilicon compounds. Herein, we describe the first protocol for the generation of silyl radicals by photoinduced decarboxylation of silacarboxylic acids, which can be easily prepared in high yield on a gram scale and are very stable to air and moisture. Irradiation of silacarboxylic acids with blue LEDs (455 nm) in the presence of a commercially available photocatalyst releases silyl radicals, which can further react with various alkenes to give the corresponding silylated products in good-to-high yields with broad functional-group compatibility. This reaction proceeds in the presence of water, enabling efficient deuterosilylation of alkenes with D₂O as the deuterium source. Germyl radicals were similarly obtained.     

Sila‐ and Germacarboxylic Acids: Precursors for the Corresponding Silyl and Germyl Radicals

Silicon‐containing compounds are widely used as synthetic building blocks, functional materials, and bioactive reagents. In particular, silyl radicals are important intermediates for the synthesis and transformation of organosilicon compounds. Herein, we describe the first protocol for the generation of silyl radicals by photoinduced decarboxylation of silacarboxylic acids, which can be easily prepared in high yield on a gram scale and are very stable to air and moisture. Irradiation of silacarboxylic acids with blue LEDs (455 nm) in the presence of a commercially available photocatalyst releases silyl radicals, which can further react with various alkenes to give the corresponding silylated products in good‐to‐high yields with broad functional‐group compatibility. This reaction proceeds in the presence of water, enabling efficient deuterosilylation of alkenes with D₂O as the deuterium source. Germyl radicals were similarly obtained.     

Copper-catalyzed synthesis of gem-difluoroallylboronates from α-trifluoromethyl alkenes and B2pin2

A novel and efficient method for the synthesis of gem-difluoroallylboronates via copper-catalyzed defluorinative borylation of α-trifluoromethyl alkenes with B₂pin₂ using Xantphos as ligand and NaOtBu as base was developed.     

Scale-up synthesis of a deuterium-labeled cis-cyclobutane-1,3-Dicarboxylic acid derivative using continuous photo flow chemistry

Continuous photo flow synthesis of tert-butyl 3-oxo-2-oxabicyclo[2.2.0]hex-5-ene-6-carboxylate (2b) from tert-butyl 2-oxo-2H-pyran-5-carboxylate (1b) has been investigated for scale-up synthesis of cis-3-(tert-butoxycarbonyl)-2,3,4-d₃-cyclobutanecarboxylic acid (3c) as a useful building block for preparation of various biologically active compounds and those of material sciences containing cyclobutane ring system(s) labeled with deuterium atoms. Optimization of reaction conditions and modification of the photo flow reaction system have brought about the production of cis-3-(tert-butoxycarbonyl)-2,3,4-d₃-cyclobutanecarboxylic acid (3c) with excellent deuterium content in 3.6?g through the continuous photo flow synthesis for 22?h followed by hydrogenation with deuterium gas. Also, application of the product to synthesis of cis-3-((benzyloxycarbonyl)methyl-d₂)cyclobutane-1,2,4-d₃-carboxylic acid (11) is described for preparation of internal standards of drug candidate compounds in quantitative mass spectrometry analyses in nonclinical and clinical pharmacokinetic studies.     

Fe- or co-catalyzed silylation-peroxidation of alkenes with hydrosilanes and T-hydro

The silylation-peroxidation of alkenes with hydrosilanes and T-hydro was developed by using iron or cobalt catalyst. The three-component protocol provided a practical method for synthesis of a variety of β-silyl peroxides. Excellent diastereoselectivity of the silylation-peroxidation of alkenes was achieved when internal alkenes were used.     

Copper‐Catalyzed Difunctionalization of Activated Alkynes by Radical Oxidation–Tandem Cyclization/Dearomatization to Synthesize 3‐Trifluoromethyl Spiro[4.5]trienones

A copper‐catalyzed difunctionalizing trifluoromethylation of activated alkynes with the cheap reagent sodium trifluoromethanesulfinate (NaSO₂CF₃ or Langlois’ reagent) has been developed incorporating a tandem cyclization/dearomatization process. This strategy affords a straightforward route to synthesis of 3‐(trifluoromethyl)‐spiro[4.5]trienones, and presents an example of difunctionalization of alkynes for simultaneous formation of two carbon–carbon single bonds and one carbon–oxygen double bond.     

Synthesis of the H-phosphonate dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide and the phospha-Michael addition to unsaturated compounds

A series of phosphonate-containing compounds based on dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO) is presented. BPPO is synthesized by a three–component condensation and is added to activated alkenes with systematically varied structure via phospha-Michael addition. Acrylates, α,β-unsaturated carboxylic acid diesters and benzoquinone are used as activated alkenes. The new compounds are characterized by ¹H, ¹³C and ³¹P NMR spectroscopy. The as-prepared phosphonates are envisioned to have flame retardant properties.