Ching Fa Yao

Cerium (IV) ammonium nitrate (CAN) as a catalyst in tap water: A simple, proficient and green approach for the synthesis of quinoxalines

Various biologically important quinoxaline derivatives have been efficiently synthesized in excellent yields using catalytic amounts of cerium (IV) ammonium nitrate (CAN) in water. This inexpensive, nontoxic, and readily available catalytic system (5 mol%) in water efficiently catalyzes the condensation reaction of various 1,2-diketones and 1,2-diamines. Several aromatic as well as aliphatic 1,2-diketones and aromatic 1,2-diamines such as substituted phenylene diamines, and tetra amines were further subjected to condensation using catalytic amounts of CAN to yield the products in excellent yield. Besides this, ambient conditions, excellent product yields and water as a universal solvent display both economic and environmental advantages.

A convenient new procedure for converting primary amides into nitriles

An operationally simple and high-yielding procedure has been developed for the conversion of primary amides to the corresponding nitriles, using ethyl dichlorophosphate/DBU as the mild dehydrating agent.

Synthesis of isocoumarin derivatives via the copper-catalyzed tandem sequential cyclization of 2- halo-N-phenyl benzamides and acyclic 1,3-diketones

A facile and rapid synthesis of isocoumarin derivatives using a copper-catalyzed tandem C-C/C-O coupling strategy from readily available substrates is described. The reactions of a wide range of 2-iodo-N-phenyl benzamides and acyclic diketones as starting materials were investigated.

Thieno[3,4‐b]thiophene‐Based Organic Dyes for Dye‐Sensitized Solar Cells

New dipolar sensitizers containing an ethyl thieno[3,4-b]thiophene-2-carboxylate (ETTC) entity in the conjugated spacer have been synthesized in two isomeric forms. These compounds were used as the sensitizers of n-type dye-sensitized solar cells (DSSCs). The best conversion efficiency (5.31%) reaches approximately 70% of the N719-based (7.41%) DSSC fabricated and measured under similar conditions. The ETTC-containing compounds exhibit a bathochromic shift of the absorption compared to their thiophene congeners due to the quinoid effect, however, charge-trapping at the ester group of ETTC was found to jeopardize the electron injection and lower the cell efficiency. Charge trapping is alleviated as the ester group of ETTC is replaced with a hydrogen atom, as evidenced from the theoretical computation.

Reactions of β-nitrostyrenes with Gragnard reagents

Abstract α-Phenyl-β-nitrostyrene 1a and β-nitrostyrene 1b react with Grignard reagents to generate hydroximoyl halides 3 or nitrile oxides 4 after workup with ice cold concentrated aqueous HX acid solution. Carboxylic acids 5 are the only products isolated from 1b and products 3 or 4 are still obtained from 1a when concentrated sulfuric acid solution is used.

Efficient TCT-catalyzed Synthesis of 1,5-Benzodiazepine Derivatives under Mild Conditions

2,4,6-Trichloro-1,3,5-triazine (TCT) efficiently catalyzed the condensation reactions between 1,2-diamines and various enolizable ketones to afford 1,5-benzodiazepines in good to excellent yields. Simple and mild reaction conditions, the use of a cheap catalyst and easy workup and isolation are notable features of this method.

Synthesis of Isoxazoline N-Oxides via [Hydroxy(tosyloxy)iodo]benzene (HTIB)-Mediated Oxidative N−O Coupling

An HTIB mediated oxidative N-O coupling strategy for the synthesis of some isoxazoline N-oxide derivatives from β-hydroxyketoximes is described, along with a comparative study of the efficiency of N-O coupling in two different solvents. A plausible mechanism for the conversion is proposed.

Naphthyl and thienyl units as bridges for metal-free dye-sensitized solar cells.

A series of new organic dyes, comprising a naphthyl moiety as a π-conjugated bridge, different amines as donors, and a cyanoacrylic acid group as an electron acceptor and anchoring group, have been designed and synthesized for applications in dye-sensitized solar cells (DSSCs). One of the compounds was also characterized by single-crystal X-ray structural analysis. All of the dyes exhibited maximum absorptions in the range of 371-441 nm. The short-circuit photocurrent density, open-circuit voltage, and fill factor (FF) values of the devices are in the range of 6.13-10.90 mA cm(-2), 0.62-0.69 V, and 0.62-0.67, respectively, corresponding to an overall conversion efficiency of 2.76-4.55%. The conversion efficiency reached 38-62% of that of a N719-based device (7.31%) fabricated and measured under similar conditions. Steric congestion between the naphthyl and aromatic moieties jeopardizes charge transfer from the donor to the acceptor. Insertion of an alkenyl entity between the naphthyl entity and the aromatic ring alleviates steric congestion and leads to longer wavelength electronic absorption spectra.

Synthesis of indolylquinolines, indolylacridines, and indolylcyclopenta[b]quinolines from the Baylis-Hillman adducts: an in situ [1,3]-sigmatropic rearrangement of an indole nucleus to access indolylacridines and indolylcyclopenta[b]quinolines.

A simple and easy route to the synthesis of a variety of structurally diverse indolylquinolines, indolylacridines, and indolylcyclopenta[b]quinoline derivatives via the reductive cyclization of C-alkylated indole derivatives, derived from acyclic as well as cyclic Baylis-Hillman adducts with indoles, is described. An unusual in situ [1,3]-sigmatropic rearrangement of the indole nucleus was observed during the reductive cyclicization of α-regioselective B-H adducts containing indoles to produce indolylacridines and indolylcyclopenta[b]quinoline derivatives.

An efficient method for the N-bromosuccinimide catalyzed synthesis of indolyl-nitroalkanes

An efficient and practical method for the synthesis of indolyl-nitroalkane derivatives catalyzed by N-bromosuccinimide is described. The generality of this method was demonstrated by synthesizing an array of diverse 3-substituted indole derivatives by the reaction of different β-nitrostyrenes with various substituted indoles. Simple reaction conditions accompanied by good yields of indolyl-nitroalkanes are the merits of this methodology.