Visible-Light-Initiated Catalyst-Free Radical Annulation Reactions of 1,6-Enynes and Aryl Sulfonyl Bromide to Assemble Sulfonation/Bromination Succinimide Derivatives.

In the present study, the environment-friendly visible-light-promoted strategy is used to perform an efficient, simple, and straightforward photocatalytic succinimide derivative synthesis from the reaction of 1,6-enynes and aryl sulfonyl bromide at room temperature under air ambient conditions. This method features mild conditions, broad substrate scope, high yields, and excellent configurational selectivity. In addition, all the atoms of the substrates involved in the reaction converge in the product structures, showing a high atomic economy. Moreover, the most important characteristic of this study is that no photocatalyst and additives are used, while the key factor that triggers the reaction is visible light, indicating that this study has an important practical value.

Three-Component Reaction for the Synthesis of Spiro-Heterocycles from Isatins, Substituted Ureas, and Cyclic Ketones.

We reported an efficient three-component reaction to access new spiro heterocycles through the annulation reactions of isatins, substituted ureas, and cyclic ketones under normal laboratory conditions, which is another example of isatins being used to build spiro compounds by the ring-opening and recyclization processes. The wide range of substrates, simple operation, normal experimental conditions, and high yields make the approach of high practical value.

Meerwein Arylation of Aryl(alkyl)idenemalononitriles and Diazonium Salts for the Synthesis of 2-(Aryl(alkyl)/arylmethylene)malononitrile Derivatives.

A metal-free Meerwein arylation reaction from aryl(alkyl)idenemalononitriles and diazonium salts for the synthesis of 2-(aryl(alkyl)/arylmethylene)malononitrile derivatives under mild conditions was well developed. Different from the general addition reactions between alkenes and diazonium salts, this study performed the traditional coupling reaction for the formation of C(sp2)-C(sp2) bond arylation products. The radical reaction mechanism was well verified in the control experiments. The other advantages of the approach are broad-scope substrates and good group tolerance. Moreover, the obtained products can be readily converted into high-value asymmetric ketones and hydrogenation reactions.

Electrochemical Radical Reactions of Enol Acetates and Free Alcohols Directly Access to α-Alkoxylated Carbonyl Compounds.

The efficient intermolecular alkoxylation reactions of various enol acetates and different alcohols are developed in the electrochemical process for the first time. Enol acetates derived from either aromatic, alkyl, or alicyclic ketones, and abundant free alcohols directly used in this synthetic strategy, make this transformation very valuable in synthesis and application in the future.

Fluorohydroxylation and Hydration Reactions of para-Quinone Methides Promoted by Selectfluor.

Selectfluor-promoted vicinal fluorohydroxylation and hydration reaction of para-quinone methides (p-QMs) were described, affording vicinal fluorohydrins and ketone/ether products in high yields. The hydration products were highly controlled by the electronic properties of substituents in the aromatic ring, and simultaneously, the amount of Selectfluor was completely different during the synthesis of ketone/ether products. This reaction also represents the first fluorohydroxylation of p-QMs, and the wide range of p-QMs makes the vicinal fluorohydroxylation of great significance.

Copper(I)-Catalyzed Radical Carbamylation/Cyclization of 2-Aryl-N-methacryloylindoles with Substituted Formamides to Assemble Amidated Indolo[2,1-a]isoquinolin-6(5H)-ones.

An efficient synthesis of amidated indolo[2,1-a]isoquinolin-6(5H)-ones has been achieved via copper(I)-catalyzed radical carbamylation/cyclization of 2-aryl-N-methacryloylindoles with substituted formamides. In this reaction, an isoquinoline ring was constructed by carbamylation of a carbon-carbon double bond in 2-arylindoles. This strategy successfully introduces the substituted amide group into the indolo[2,1-a]isoquinoline skeleton and has advantages such as wide substituent scope, mild reaction conditions, high regioselectivity, and good to excellent yields.

Electrochemical Radical Reaction Construction of C-C Bonds: Access to 1,4-Dicarbonyl Compounds from Enol Acetates and 1,3-Diketones.

As important substrates for the construction of heterocycles, a simple and efficient approach for synthesis of 1,4-diones is highly desirable. In this work, novel and efficient electrochemical radical reactions of enol acetates and 1,3-diketones have been developed to successfully achieve 1,4-diketones under catalyst-free and oxidant-free conditions. The wide range of substrates, good group tolerance, and simple operation process make the approach have important practical value. Moreover, the obtained 1,4-diketones can be easily further transformed to pyrrole and furan derivatives.

Construction of Spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione Derivatives via Ring-Opening and Recyclization of Isatins and C-OH Cleavage of 2-Naphthol.

An efficient three-component reaction to access spiro[benzo[a]acridine-12,4'-imidazolidine]-2',5'-dione derivatives has been developed through the ring-opening and recyclization process of isatins and dehydroxylation of 2-naphthol, which is different from their conventional reaction modes. Experimental observations suggest that p-toluenesulfonic acid is the key factor that promotes the success of this synthetic strategy. The research provided a novel approach for the construction of spiro compounds from isatins and 2-naphthol in organic synthesis.

Propargyl Chalcones' Radical Annulation/Sulfonation Reaction: Efficient Synthesis of Benzo[b]oxepin-5(2H)-one and Chromane Derivatives.

A novel and facile methodology for the synthesis of sulfonated benzo[b]oxepinone and chromane derivatives was reported by the reaction of propargyl chalcones with arylsulfonyl chloride via radical cascade annulation/sulfonation under laboratory conditions. Readily available propargyl chalcones, commercialized arylsulfonyl chloride, and simple reaction conditions make this six(seven)-membered oxygen-containing heterocycles' synthetic strategy more attractive and with significant application values.

Silver-Catalyzed Radical Cascade Sulfonation/Cycloaddition for the Construction of Multifunctional Succimides Containing Separable Z/E-Isomers.

A silver-catalyzed cascade cycloaddition of aza-1,6-enynes, affording multifunctional succimide frameworks initiated by the arylsulfonyl radical addition, has been developed. This process shows mild reaction conditions, excellent structural selectivity, and broad functional group tolerance. In addition, the Z/E-isomers can be easily separated, which provides an efficient method for obtaining pure Z/E-configuration products.

Electrochemical Radical δ-H Sulfonylation Reaction for the Synthesis of 4-((Aryl,Arylsul fonyl)methylene)-2,5-Cyclohexadiene Derivatives.

A novel and efficient electrochemical radical δ-H sulfonylation reaction of para-quinone methides (p-QMs) and sodium sulfinates has been achieved under common laboratory conditions. In this strategy, a new C(sp2)-S bond was constructed for the synthesis of 4-((aryl,arylsulfonyl)methylene)-2,5-cyclohexadiene derivatives with a broad substrate scope, good functional group tolerance, and mild conditions. Further studies showed that the reaction had an excellent regional selectivity.

Copper-Catalyzed Annulation Reaction of Alkenes and N-Alkyl(aryl)-1-(methylthio)-2-nitroethenamine: an Approach for the Synthesis of Isoxazole Derivatives.

A copper-catalyzed annulation reaction to access a variety of isoxazoles from alkenes and oxazete in situ generated from N-alkyl(aryl)-1-(methylthio)-2-nitroethenamine was reported. A plausible mechanism underlying the formation of the product was proposed, which represented a new approach for the construction of isoxazolines. This reaction was capable of tolerating alkenes bearing various substituents, which showed a relatively broad substrate scope with good functional group compatibility.

Ru-Catalyzed δ-Arylation of para-Quninone Methides with Aryl Diazonium Salts to Synthesize Fuchsones.

A novel reaction mode and efficient ruthenium-catalyzed Matsuda-Heck-type arylation of para-quinone methides (p-QMs) with aryl diazonium salts has been developed for the synthesis of symmetrical or unsymmetrical δ,δ'-diaryl quinone methides (fuchsones). Aryl groups are introduced at the δ-position of p-QMs via tandem olefin insertion reaction/ß-H elimination processes. This reaction features advantages such as mild and green conditions, broad reactant scope, and high yields.

An efficient and green reaction of isatins, 3-amino-1-phenyl-2-pyrazolin-5-one (3-amine-1H-pyrazole), and ß-diketone in aqueous medium.

An efficient and green reaction of isatins, 3-amino-1-phenyl-2-pyrazolin-5-one (3-amine-1H-pyrazole), and [Formula: see text]-diketone in aqueous medium in the presence of [Formula: see text]-[Formula: see text] is reported, and a series of novel spirocompounds was obtained with high yields. The advantages of this reaction were simple procedure, moderate reaction conditions, and wide range of substrates. More importantly, the catalyst [Formula: see text]-[Formula: see text] could be recovered for reuse up to five times.

Catalytic hydrogenation of cyclic carbonates: a practical approach from CO2 and epoxides to methanol and diols.

Two birds with one stone: the simultaneous production of two important bulk chemicals, methanol and ethylene glycol, from CO(2) and ethylene oxide has been achieved under mild conditions by the highly efficient homogeneous catalytic hydrogenation of ethylene carbonate in the presence of a (PNP)Ru(II) catalyst.

Metal-Free Radical Annulation of Oxygen-Containing 1,7-Enynes: Configuration-Selective Synthesis of (E)-3-((Arylsulfonyl)methyl)-4-Substituted Arylidenechromene Derivatives.

A novel strategy for the synthesis of (E)-3-((arylsulfonyl)methyl)-4-substituted benzylidenechromene derivatives via a metal-free radical annulation reaction of oxygen-containing 1,7-enynes with thiosulfonates has been developed. The reaction shows broad substrate scope, wide functional group tolerance, and moderate to excellent yields. Moreover, thiosulfonates were well driven to achieve the bifunctionalization reaction of oxo-1,7-enynes which derived from aliphatic alkynes. In addition, the (E)-configuration of the products was highly controlled by the structure of 1,7-enyne.

Time-Economical Radical Cascade Cyclization/Haloazidation of 1,6-Enynes: Construction of Highly Functional Succinimide Derivatives.

A "time-economical" radical cascade cyclization/haloazidation of 1,6-enynes provides a direct approach to access highly functional succinimide compounds. Moderate to excellent yields along with excellent Z/E ratio were obtained under the reaction features of broad substrate scope, good functional group tolerance, and mild reaction conditions.

4-(4-Fluoro-phen-yl)-2-oxo-1,2,5,6-tetra-hydro-benzo[h]quinoline-3-carbonitrile.

In the mol-ecule of the title compound, C(20)H(13)FN(2)O, the fluoro-phenyl ring is oriented at a dihedral angle of 72.76 (3)° with respect to the fused benzene ring. In the crystal structure, inter-molecular N-H⋯O, C-H⋯O and C-H⋯F inter-actions link the mol-ecules into chains. π-π contacts between the quinoline and benzene rings [centroid-centroid distance = 3.918 (3) Å] may further stabilize the structure. A weak C-H⋯π inter-action is also present. The O atom and two of the CH(2) groups of the quinoline ring system are disordered over two positions. The O atom was refined with occupancies of 0.489 (17) and 0.511 (17), while C and H atoms were refined with occupancies of 0.435 (13) and 0.565 (13).

Characterization of a bio-oil from pyrolysis of rice husk by detailed compositional analysis and structural investigation of lignin.

Detailed compositional analysis of a bio-oil (BO) from pyrolysis of rice husk was carried out. The BO was extracted sequentially with n-hexane, CCl(4), CS(2), benzene and CH(2)Cl(2). In total, 167 organic species were identified with GC/MS in the extracts and classified into alkanes, alcohols, hydroxybenzenes, alkoxybenzenes, dioxolanes, aldehydes, ketones, carboxylic acids, esters, nitrogen-containing organic compounds and other species. The benzene ring-containing species (BRCCs) were attributed to the degradation of lignin while most of the rests were derived from the degradation of cellulose and hemicellulose. Along with guaiacyl and p-hydroxyphenyl units as the main components, a new type of linkage was suggested, i.e., C(ar)-CH(2)-C(ar) in 4,4'-methylenebis(2,6-dimethoxyphenol). Based on the species identified, a possible macromolecular structure of the lignin and the mechanism for its pyrolysis are proposed. The BO was also extracted with petroleum ether in ca. 17.8% of the extract yield and about 82.1% of the extracted components are BRCCs.