Potassium Ferricyanide Oxidative Cyclizationof Arylaldehyde with o-Phenylenediamine and o-Aminophenol to 2-Arylbenzimidazoles and 2-Arylbenzoxazoles

Some new benzimidazoles and benzoxazoles have been prepared under mild condition by oxidative cyclization of arylaldehyde witho-phenylenediamine ando-aminophenol using potassium ferricyanide as oxidant

A Pd(Ⅱ)-Catalyzed Oxidative Cyclization for the Preparation of AryI-Fused Six-Membered Nitrogen Heterocycles with 2-Acetoxy Functionality

A Pd（II）-catalyzed oxidative cyclization of olefinic tosylamides was developed for the preparation of aryl-fused and N-containing six-membered heterocycles. Under optimized conditions the reaction proceeded with high activity and selectivity, with yields of up to 83% being obtained. This procedure provides a facile and efficient route to the aforementioned heterocycles with 2-acetoxy functionality.

Metal-free visible-light-induced oxidative cyclization reaction of 1,6-enynes and arylsulfinic acids leading to sulfonylated benzofurans

A new and convenient visible-light-induced method has been developed for the synthesis of sulfonylated benzofurans via oxidative cyclization reaction of 1,6-enynes and arylsulfinic acids.This reaction was carried out under metal-free and mild conditions,in which the C-S,C-C and C=O bonds could be sequentially formed in one pot operation.

One-pot aqueous-phase synthesis of quinoxalines through oxidative cyclization of deoxybenzoins with 1,2-phenylenediamines catalyzed by a zwtterionic Cu(Ⅱ)/calix[4]arene complex

A green protocol for the synthesis of quinoxalines has been developed from catalytic oxidative cyclization of deoxybenzoins with 1,2-phenylenediamines in water.The optimal conditions are involved in the use of a water-soluble mononuclear copper（Ⅱ） complex of a zwitterionic calix[4]arene[Cu（Ⅱ）LCH2O）]I2（1,H4L=[5,ll,17,23-tetrakis（trimethylammonium）-25,26,27,28-tetrahydroxycalix[4]arene]） as a catalyst in alkali solution after refluxing for 15 h in O2.The target quinoxaline and its derivatives were obtained in good yields（up to 88%）.The procedure described in this paper is simple,practical and environmentally benign.

Facile Synthesis of 5-Trifluoromethyl-2,4-disubstituted Oxazoles via a Copper（Ⅱ）-Catalyzed and TBHP/I2- Mediated Tandem Oxidative Cyclization

In the presence of Cu（OAc）2·H2O, a variety of 5-trifluoromethyl-2,4-disubstituted oxazoles were easily synthesized via t-BuOOH （TBHP）/I2-mediated tandem oxidative cyclization from readily available starting materials aryl methanamines and α-trifluoroacetyl-substituted ketones or esters under mild conditions, The mechanism was proposed.

Metal-free synthesis of 3-trifluoromethyl-1,2,4-triazoles via oxidative cyclization of trifluoroacetimidohydrazides with N,N-dimethylformamide as carbon synthons

A metal-free approach for the synthesis of 3-trifluoromethyl-1,2,4-triazoles via I2-mediated oxidative cyclization of readily accessible trifluoroacetimidohydrazides with N,N-dimethylformamide(DMF)has been disclosed.In this transformation,the commonly used organic solvent DMF is applied as a C1 synthon and the methine unit of the 1,2,4-triazole products is independently from N-methyl and N-acyl of DMF.The application potential of the developed method has been demonstrated by the synthesis of the key skeleton of factor IXa inhibitors.

I_(2)/Ph I(OAc)2-assisted oxidative C–H amination protocols toward metal-free pragmatic synthesis of pyrrolo[2,3-b]indoles

We report herein an I2/Ph I(OAc)2catalytic system for the pragmatic construction of C–N bonds through C–H/N–H oxidative coupling protocol.Divergent pyrrolo[2,3-b]indoles were efficiently prepared via I2-catalyzed intramolecular C–H amination reactions from(E/Z)-2-indolylenamines under metal-free conditions.Various functional groups are tolerated under mild reaction conditions and the resulting pyrrolo[2,3-b]indoles were obtained with mostly good to excellent yields.It was interesting to observe that both the(E)-and(Z)-isomers of the starting materials were efficiently transformed into the targeted product.The I+-mediated catalytic cycle was proposed based on mechanistic studies for this reaction.

The First Total Synthesis of the （±）-Palstatin

The first total synthesis of （±）-palstatin was achieved from commercially available 5-bromovanallin and 2,4,6-trihydroxyacetophenone. SeO2 promoted oxidative cyclization reaction and Ag20 catalyzed oxidative coupling reaction served as the key steps in the synthesis successfully.

Rhodium catalyzed regioselective arene homologation of aryl urea via double C–H bond activation and migratory insertion of alkyne

A convenient rhodium catalyzed oxidative arene homologation of aniline derivatives with symmetrical or unsymmetrical alkynes using Cu（OAc）2 as oxidant is described. Urea group is shown to be effective as a directing group for initial ortho C–H activation. Two migratory insertion events of alkyne into Rh–C bond occur successively, both with complete regioselectivity. This method is particularly useful for synthesis of polyarenes with different substituents, which has not been reported with conventional protocol. A mechanism has been proposed to explain the observed data.

Facile synthesis and characterization of a novel thiophene-fused polycyclic aromatics based on pyrene

A novel large thiophene-fused polycyclic aromatics 1 based on pyrene 5 has been synthesized, and its structure was confirmed by ^1H NMR, ^13C NMR, MS, UV-vis and elemental analysis. The key steps of the synthesis involved the Stille cross-coupling reaction and followed by selective β-β oxidative cyclization of pendant thienyl rings by FeCl3 under mild conditions.

Molecular Iodine Promoted Synthesis of New Pyrido[2,3-d]pyrimidin-4-ols

A highly efficient synthesis of novel pyrido[2,3-d]pyrimidin-4-ols was developed via an iodine-catalyzed tandem oxidative cyclization under focused microwave irradiation. Pyrido[2,3-d]pyrimidin-4-ols were obtained from easily available 2-amino-4-aryl-6-arylnicotinamides and benzylic amines with good to excellent yields.

A total synthesis of (+)-preussin and its 5-epimer

(+)-Preussin (1) and its 5-epimer were synthesized from the divinylcarbinol (3) with Sharpless asymmetric epoxidation of 3 and the oxidative cyclization of 9 with PDC as the key steps.