Yiyuan Peng

Synthesis of 2-aminobenzothiazole via FeCl3-catalyzed tandem reaction of 2-iodoaniline with isothiocyanate in water

An FeCl3-catalyzed tandem reaction of 2-iodoaniline with isothiocyanate in water is described, which provides an environmentally benign, efficient, and practical route for the generation of 2-aminobenzothiazole. This present tandem process shows broad substrate scope in the presence of octadecyltrimethylammonium chloride as a phase-transfer catalyst. In addition, the reaction media can be recovered and recycled without loss of efficiency.

Silica Gel-Promoted Tandem Addition−Cyclization Reactions of 2-Alkynylbenzenamines with Isothiocyanates

Tandem addition-cyclization reactions of 2-alkynylbenzenamines with isothiocyanates promoted by silica gel are described. This reaction proceeds smoothly at 80 degrees C under metal- and solvent-free conditions, which provides an efficient and practical route for the generation of 2,4-dihydro-1H-benzo[d][1,3]thiazines. The recovered silica gel could be reused for several times.

Directing‐Group‐Assisted Transition‐Metal‐Catalyzed Direct Intermolecular C−H Amidation and Amination of Arenes

This review focuses on the most recent advances in the field of transition‐metal‐catalyzed direct intermolecular C−H amidation and amination of arenes. The manuscript is divided into two parts according to whether or not external oxidants are required. The first part includes the cases of simple neutral amines, amides, or sulfonamides in combination with external oxidants. The second section contains the examples of preactivated amino sources in the absence of any external oxidants. In each part, the content is classified in line with the different types of transition‐metal catalysts used, including Rh, Ru, Ir, Pd, Cu, Ni, Co, and Fe. In addition, the substrate scope and limitations as well as catalytic mechanism are discussed.

Efficient assembly of 1-(1H-imidazol-1-yl)-3-methylene-1H-indenes via tandem reaction of (2-(alkynyl)benzylidene)malonates with imidazoles.

The tandem nucleophilic addition and 5-exo-cyclization of (2-(alkynyl)benzylidene)malonates with imidazole derivatives in the presence of t-BuOK is reported. This reaction proceeds smoothly under mild conditions with high selectivity to afford the corresponding 1-(1H-imidazol-1-yl)-3-methylene-1H-indene-2,2(3H)-dicarboxylates in good to excellent yields.

Iron-catalyzed one-pot synthesis of 2-aminobenzothiazoles from 2-aminobenzenethiols and isothiocyanates under ligand-free conditions in water

A practical and efficient method for the synthesis of 2-aminobenzothiazoles has been developed via an iron-catalyzed one-pot tandem reaction. Various 2-aminobenzothiazoles were conveniently synthesized in moderate to excellent yields. It is highlighted that the reaction is conducted under ligand-free conditions in water.

Merging Asymmetric Henry Reaction with Organocatalytic Cascade Reaction for the Construction of a Chiral Indolizidine Alkaloid Skeleton

A sequential reaction combining the copper-catalyzed asymmetric Henry reaction with the organocatalytic Michael addition-hemiacetalization cascade reaction was developed. The C1-symmetric chiral diamine L1-copper complex was responsible for the first highly enantioselective Henry reaction, while diphenylprolinol silyl ether A acted as effective organocatalyst for the second cascade reaction between chiral β-nitro alcohol and α,β-unsaturated aldehydes. Via rational design and combination of the two independent catalytic systems, good yields and excellent enantioselectivities and diastereoselectivities were achieved for a broad substrate scope under mild reaction conditions. The synthetic utility of this sequential catalytic asymmetric cascade reaction was demonstrated as an alternative and straightforward stereoselective synthesis strategy for chiral indolizidine alkaloid and its analogues.

Quinazolinone derivatives: Synthesis and comparison of inhibitory mechanisms on α-glucosidase

In this study, eight quinazolinone derivatives were designed and synthesized. Their inhibitory activities on α-glucosidase were assessed in vitro. Two compounds: 2-(4-chlorophenyl)-quinazolin-4(3H)-one (CQ) and 2-(4-bromophenyl)-quinazolin-4(3H)-one (BQ) were found to be potent inhibitors of α-glucosidase with IC50 values of 12.5±0.1μM and 15.6±0.2μM, respectively. Spectroscopy methods were performed to analyze the inhibitory mechanisms of both compounds on α-glucosidase. The results revealed that they reversibly inhibited α-glucosidase in a non-competitive manner. CQ and BQ could statically quench the fluorescence spectra by formation of an inhibitor-α-glucosidase complex. The interaction between CQ and α-glucosidase depended on hydrogen bonds, electrostatic and hydrophobic force, while the driving force of the binding between BQ and the enzyme was hydrophobic. The docking results showed that BQ was less active than CQ against α-glucosidase because of its weaker interaction with the enzyme. In brief, the quinazolinone derivatives identified in this work were potentially promising candidates for developing as novel anti-diabetic agents.

New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

Summary A new simple and efficient method to construct ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives has been developed from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles under mild conditions, without the need for a metal catalyst. The newly developed method tolerates a wide range of substrates in moderate to excellent yields. Moreover, this method is advantageous over previous ones for the easy synthesis of reactants.

Synthesis of 2-trifluoromethylquinolines via copper-mediated intramolecular oxidative cyclization of N-(2-alkenylaryl) enamines

A general and efficient copper-mediated intramolecular oxidative cyclization of N-(2-alkenylaryl) enamines for the synthesis of 2-trifluoromethylquinolines has been developed. The targeted heterocycle is a privileged structure in many natural compounds and drugs with a broad range of biological activities.

Iron-Catalyzed Tandem Reactions of ortho-Aminobenzenethiols with Isothiocyanates Leading to 2-Aminobenzoazoles Under Ligand- and Solvent-Free Conditions

Abstract An efficient route to synthesize a variety of 2-aminobenzoazoles has been discovered. It involves the reaction of ortho-aminobenzenethiols with isothiocyanates via iron-catalyzed tandem addition-annulations process under ligand and solvent free conditions on silica gel surface. GRAPHICAL ABSTRACT