Search

Hydrogen binding of molecules on specific solid surface is an attractive interaction that can be employed as driving force for chemical bond activation, material directed assembly, protein protection, etc. However, the lack of quantitative characterization method for hydrogen bonds (HBs) on surface seriously limits its application. Herein, we measured the standard Gibbs free energy change (ΔG 0 ) of surface HBs using NMR technique. HBs accepting ability of surface was investigated in term of comparing ΔG 0 values by employing model biomass platform 5-hydroxymethylfurfural on a series of Co-N-C-n catalysts with electron-rich doped-nitrogen contents adjusted. Reducing the ΔG 0 effectively improves HBs accepting ability of the nitrogen-doped surface, and promotes the O-H bonds selectively initiated activation in the oxidation of 5-hydroxymethylfurfural. As a result, the reaction kinetics is accelerated and the rate constant is significantly increased. In addition to excellent catalytic performance, the turnover frequency (TOF) value for this oxidation is extremely higher than the reported non-noble metal catalysts.

“CN” generation from formamide dehydration! A novel Ni-catalyzed hydrocyanation of various alkenes to provide aliphatic nitriles is developed by generating hydrocyanic acid in situ from safe and readily available formamide. Excellent linear or branched regio-selectivity, wide substrate scope, cheap and stable nickel salt as a pre-catalyst, a safe cyano source, slow generation of “CN” to obviate catalyst deactivation and convenient experimental operation would render this hydrocyanation attactive for laboratory synthesis of aliphatic nitriles.

The in situ generation of a “cyano” unit from readily available organic precursors is of high interest in synthetic chemistry. Herein, we report the first example of Ni-mediated dehydration of formamide to form “CN” and its subsequent catalytic applications in the hydrocyanation of alkynes and cyanation of aryl halides. Formamide can serve as a convenient source for the nitrile unit, in that it releases water as the only byproduct.

A convenient Co-catalyzed three-component decarbonylative alkylative esterification of styrene derivatives with aliphatic aldehydes and iodobenzene diacetate to provide chain elongated acetates and benzoates has been developed. Readily available aliphatic aldehydes are decarbonylated into 1°, 2° and 3° alkyl radicals for the construction of a C(sp3)–C(sp3) bond via radical addition and an interconversion of CoII–CoIII–CoI complexes is accountable for the formation of a C(sp3)–O bond.

A convenient Fe-catalyzed decarbonylative alkylation–peroxidation of alkenes with aliphatic aldehydes and TBHP to provide chain elongated peroxides is developed, which is further applied to the one-pot synthesis of alkylated ketones. Aliphatic aldehydes were decarbonylated into 1°, 2° and 3° alkyl radicals at low temperature which subsequently allows the cascade construction of C(sp3)–C(sp3) and C(sp3)–O bonds via radical insertion and radical–radical coupling. Various alkenes including mono-substituted, terminally disubstituted or internally disubstituted styrenes bearing synthetically useful functional groups and electron-poor acrylates were tolerated.

From difunctionalization of a single alkene to radical-dual-difunctionalization of two different alkenes! Abundant aliphatic aldehydes were readily decarbonylated into alkyl radicals for the cascade construction of C(sp3)-C(sp3), C(sp3)-C(sp3) and C(sp3)-O bonds via double radical addition and radical-radical coupling, following the intrinsic nucleophilic/electrophilic reactivity of both the radicals and alkenes.

A practical zinc acetate dihydrate catalyzed reductive amination of various carbonyl compounds with DMF as Me2N source, reductant and solvent is developed. This reaction shows broad substrate scope, good functionality tolerance, avoids pressure-proof reactor and column chromatograph isolation with up to 98 % yield, to make it an attractive method for the preparation of N,N-dimethyl tertiary amines.

Reported herein is a novel iron-catalyzed, DTBP-mediated carboazidation of alkenes using cycloalkanes, CH2Cl2, CHCl3 and CCl4 as alkylating reagents to generate electrophilic or nucleophilic alkyl radicals. Mechanistic studies suggested that the reaction proceeded via the addition of alkyl radicals to alkenes followed by an iron-mediated ligand transfer process. The reaction is unique as it is applicable not only to diversely functionalized electron rich alkenes, but also to electron-poor olefins to provide chain extended azides and γ-azido chloroalkanes in good to high yields.

A practical iodine-catalyzed oxidative functionalization of isoquinolines with methylarenes is developed, which can be triggered by the selected oxidants to produce C1- or N-benzyl-substituted products selectively. This method utilizes readily available isoquinolines and methylarenes as starting materials and proceeds under metal-free conditions with broad substrate scope with respect to methylarenes, avoiding the usage of expensive metal catalysts and generation of halide and metal wastes.

A practical Fe-catalyzed decarbonylative cascade reaction of N-aryl cinnamamides with aliphatic aldehydes to provide C3 alkylated 3,4-dihydroquinolin-2(1H)-ones is developed. Aliphatic aldehydes were oxidatively decarbonylated into 1°, 2° and 3° alkyl radicals conveniently, allowing for the subsequent cascade construction of C(sp3)–C(sp3) and C(sp3)–C(sp2) bonds via radical addition and HAS-type cyclization. The importance of the amide linkage and the selectivity of the 6-endo-trig over 5-exo-trig cyclization pathway were elucidated by experimental results and DFT calculations.

An efficient and practical iodine-catalyzed oxidative functionalization of azaarenes with benzylic C-H bonds via an N-alkylation and amidation cascade is developed to provide isoquinolin-1(2H)-ones. This method utilizes readily available unfunctionalized azaarenes and methylarenes as starting materials and proceeds under metal-free conditions with good to excellent yields, avoiding the use of expensive noble metal catalysts and generation of halide and metal wastes. The synthetic utility of this reaction is exemplified by the concise, two-step synthesis of isoindolo[2,1-b]isoquinolin-7(5H)-one.

A general copper/air catalytic system for intramolecular N–N bond formation via oxidative dehydrogenative coupling was developed. This research provides an alternative approach for the facile synthesis of N,N′-diaryl indazol-3-one derivatives.

For the convenient introduction of simple linear/branched alkyl groups into biologically important azaspirocyclohexadienones, a practical Fe-catalyzed decarbonylative cascade spiro-cyclization of N-aryl cinnamamides with aliphatic aldehydes to provide alkylated 1-azaspiro-cyclohexadienones was developed. Aliphatic aldehydes were oxidative decarbonylated into primary, secondary and tertiary alkyl radicals conveniently and allows for the subsequent cascade construction of dual C(sp3)-C(sp3) and C=O bonds via radical addition, spirocyclization and oxidation sequence.

A convenient Fe-catalyzed decarbonylative alkylation–azidation cascade reaction of styrene derivatives with aliphatic aldehydes and TMSN3 to provide aliphatic azides is developed. With DTBP as an oxidant and radical initiator, this reaction smoothly converts aliphatic aldehydes into 1°, 2° and 3° alkyl radicals and subsequently allows for the cascade construction of C(sp3)–C(sp3) and C(sp3)–N bonds via radical insertion and nucleophilic azidation.

An efficient method for a copper-catalyzed intramolecular C-C bond cleavage to construct 2-substituted quinazolinones has been developed. The C-C bond at the 2-position of 2,2-disubstituted-1,2,3,4-tetrahydroquinazolinone was selectively cleaved by a Cu/air catalytic system. The trend for the cleavage was dependent on the leaving group in the order of: alkyl > methyl > phenyl > substituted aryl. The process described herein provides an explanation for the mechanism of the reaction between substituted 2-halobenzamides and a-substituted arylmethanamines to construct 2-substituted quinazolinones, which were previously reported and limited to the construction of 2-arylquinazolinones.

A novel method for achieving a copper(II)-catalyzed domino reaction for the construction of 2-aryl quinazolinones, without the addition of any ligand and additive, has been developed. The domino reaction achieved N-(alpha-substituted)benzylation, benzylic C-H amidation, and C-C (or C-H) bond cleavage. (C) 2014 Li-Xia Wang and Ya-Lin Tang. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. All rights reserved.

A rhodium-catalyzed oxidative decarbonylative Heck-type coupling of aromatic aldehydes with terminal alkenes to afford 1,2-disubstituted alkenes with good regio- and E-selectivity is developed. This reaction employs readily available aromatic aldehydes as the aryl electrophile counterpart and relies on selected acyl chloride as the crucial additive to activate the rhodium catalyst precursor.

A metal-free oxidative decarbonylative coupling of aromatic aldehydes with electron-rich or electron-deficient arenes to produce biaryl compounds was developed. This novel coupling was proposed to proceed via a non-chain radical homolytic aromatic substitution (HAS) type mechanism, based on the substrate scope, ortho-regioselectivity, radical trapping experiments and DFT calculation studies. With the ready availability of aromatic aldehydes and arenes, metal-free conditions should make this coupling attractive for the biaryl synthesis.

A convenient Pd-catalyzed cross-coupling of two different enamides is developed to afford the head-to-tail heterodimerization products predominately in ( Z )-configuration and up to 93% yield, with good chemo- and regioselectivity.

An iodine-catalyzed multiple C–H bond functionalization of isoquinolines with methylarenes via a successive benzylic sp3 C–H iodination/N-benzylation/amidation/double sp2 C–H oxidation sequence is developed. This reaction utilizes un-functionalized isoquinolines and readily available methylarenes as starting materials, proceeds under metal-free conditions, and avoids a multi-step experimental operation, to make it an efficient and practical method for the synthesis of N-benzyl isoquinoline-1,3,4-triones.

A silver-mediated oxidative vinylic C–H bond sulfenylation of enamides was developed. This method is compatible with diaryl and dialkyl disulfides to deliver the biologically precious chalcogenated olefins efficiently. A plausible non-chain radical mechanism was proposed for understanding this novel sulfenylation based on the mechanistic studies.

Iodine-catalyzed selective 2-arylsulfonyl indole formation from indoles and sodium sulfinates is disclosed. Various substituted 2-arylsulfonyl indoles were obtained in one pot in the absence of metal catalyst at room temperature under air.

Constructing biaryls through direct aromatic C-H functionalization of unactivated arenes has become a popular topic in organic chemistry. Many efficient methods have been developed. In this Communication, a direct arylation of unactivated arenes with a broad range of aryl iodides is reported. This reaction proceeds through a new type of amine-catalyzed single electron transfer initiated radical coupling procedure to form biaryls in high yields under UV irradiation at room temperature. Only 20 mol% of TMEDA is used as the catalyst. No other additives are required for this transformation, thus avoiding the use of toxic transition metal catalysts, strong bases, or large amounts of other organic additives. This greener protocol provides a new strategy to achieve direct aromatic C-H functionalization and offers a new example of cost-effective and environmentally benign access to biaryls.

An electrophilic amidation via a cationic rhodium(III)-catalyzed C(sp2)H activation has been developed with the commercially available N-fluorobenzenesulfonimide as the amino source under external oxidant-free conditions. This amidation requires only a catalytic amount of base and exhibits excellent functional group tolerance and regioselectivity, providing a new avenue in direct C(sp2)H amidation.

An efficient and practical iodine-catalyzed oxidative functionalization of azaarenes with benzylic C–H bonds via an N-alkylation and amidation cascade is developed to provide isoquinolin-1(2H)-ones. This method utilizes readily available unfunctionalized azaarenes and methylarenes as starting materials and proceeds under metal-free conditions with good to excellent yields, avoiding the use of expensive noble metal catalysts and generation of halide and metal wastes. The synthetic utility of this reaction is exemplified by the concise, two-step synthesis of isoindolo[2,1-b]isoquinolin-7(5H)-one.

The coupling of various readily available aromatic aldehydes with terminal alkenes leads to 1,2-disubstituted alkenes with good regioselectivity and in most cases a E:Z ratio of

An efficient method for a copper-catalyzed intramolecular C-C bond cleavage to construct 2-substituted quinazolinones has been developed. The C-C bond at the 2-position of 2,2-disubstituted-1,2,3,4-tetrahydroquinazolinone was selectively cleaved by a Cu/air catalytic system. The trend for the cleavage was dependent on the leaving group in the order of: alkyl > methyl > phenyl > substituted aryl. The process described herein provides an explanation for the mechanism of the reaction between substituted 2-halobenzamides and a-substituted arylmethanamines to construct 2-substituted quinazolinones, which were previously reported and limited to the construction of 2-arylquinazolinones.

A novel rhodium-catalyzed desulfinative coupling between aldehydes and arenesulfinic acid sodium salts was developed, generating a new protocol for the synthesis of aryl ketones. Most importantly, the coupling reaction uses molecular oxygen (O 2 ) as the oxidant and finally releases sodium hydrogen sulfate (NaHSO 4 ) from the reaction system; furthermore, this reaction occurs without the need for any additives.

An efficient Grignard-type arylation of aldehydes via aryl C―H activation was achieved under mild conditions catalyzed by rhodium. The reaction provides an easy access to a wide variety of benzyl alcohols and can tolerate various functional groups as well as air and water.

The decarbonylative coupling of aldehydes and norbornene analogues was realized for the first time by using a rhodium(I) catalyst.

A novel rhodium-catalyzed decarbonylative reaction of aldehydes with unsaturated carbonyl compounds was discovered to generate Heck-type reaction product and conjugate addition product.

Catalyzed by FeCl(3) under very mild conditions, tertiary enamides underwent a highly efficient intramolecular enaminic addition reaction to the ketonic carbonyls followed by 1,3-hydroxy rearrangement to produce 5-hydroxy-1H-pyrrol-2(5H)-ones in excellent yields.

Correction for ‘Fe-Catalyzed three-component carboazidation of alkenes with alkanes and trimethylsilyl azide’ by Wei-Yu Li et al., Chem. Commun., 2018, DOI: 10.1039/c8cc05090b.

[structure: see text]. Catalyzed by CuI/N,N-dimethylglycine, oxiranecarboxamides underwent a highly efficient and stereoselective N-vinylation reaction with (Z)-1-aryl-2-bromoethenes to afford the corresponding enamides. The method has been applied to a straightforward synthesis of (-)-(2R,3S)-SB204900, the enantiomer of the natural product. Following a hypothetic biomimetic pathway, both (+)-(5R,6S)-xi-Clausenamide and (-)-(5R,6S)-balasubramide have been efficiently synthesized for the first time through the unprecedented intramolecular 8-endo-epoxy-arene cyclization of (Z)-N-(phenylvinyl)oxiranecarboxamides.

The reaction tolerates a range of aryl and hetarylmethanamines and delivers the products in moderate to high yields.

The constant-volume combustion energies of the lead salts of 2-hydroxy-3,5-dinitropyridine (2HDNPPb) and 4-hydroxy-3,5-dinitropyridine (4HDNPPb), ΔUc (2HDNPPb(s) and 4HDNPP(s)), were determined as –4441.92±2.43 and –4515.74±1.92 kJ mol–1 , respectively, at 298.15 K. Their standard enthalpies of combustion, Δcm H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K), and standard enthalpies of formation, Δrm H θ(2HDNPPb(s) and 4HDNPPb(s), 298.15 K) were as –4425.81±2.43, –4499.63±1.92 kJ mol–1 and –870.43±2.76, –796.65±2.32 kJ mol–1 , respectively. As two combustion catalysts, 2HDNPPb and 4HDNPPb can enhance the burning rate and reduce the pressure exponent of RDX–CMDB propellant.

Constructing biaryls through direct aromatic C-H functionalization of unactivated arenes has become a popular topic in organic chemistry. Many efficient methods have been developed. In this Communication, a direct arylation of unactivated arenes with a broad range of aryl iodides is reported. This reaction proceeds through a new type of amine-catalyzed single electron transfer initiated radical coupling procedure to form biaryls in high yields under UV irradiation at room temperature. Only 20 mol% of TMEDA is used as the catalyst. No other additives are required for this transformation, thus avoiding the use of toxic transition metal catalysts, strong bases, or large amounts of other organic additives. This greener protocol provides a new strategy to achieve direct aromatic C-H functionalization and offers a new example of cost-effective and environmentally benign access to biaryls.

Iodine-catalyzed selective 2-arylsulfonyl indole formation from indoles and sodium sulfinates is disclosed. Various substituted 2-arylsulfonyl indoles were obtained in one pot in the absence of metal catalyst at room temperature under air.

The reaction requires only catalytic amount of a base and proceeds under oxidant-free conditions.

A practical Bronsted acid promoted benzylic C–H functionalization of 2-methylazaarenes and nucleophilic addition to aldehydes was developed in good to excellent yields. A six-membered hydrogen-bonding transition state is proposed to be crucial for the reaction. Ready availability of the two starting materials, the use of acetic acid as the catalyst and the facile reaction conditions will guarantee this synthetic method attractive to the synthesis of bioactive pyridine and quinoline derivatives.

A novel Pd-catalyzed desulfitative direct arylation of azoles takes place in the presence of Cu(II) as an oxidant.

The reaction does not require any additive and tolerates a variety of functional groups in the aromatic aldehydes.