Baoxiang Hu

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

Summary A general and facile one-pot protocol for the preparation of a broad range of alkyl and aryl isothiocyanates has been developed from their corresponding primary amines under aqueous conditions. This synthetic process involves an in situ generation of a dithiocarbamate salt from the amine substrate by reacting with CS2 followed by elimination to form the isothiocyanate product with cyanuric acid as the desulfurylation reagent. The choice of solvent is of decisive importance for the successful formation of the dithiocarbamate salt particularly for highly electron-deficient substrates. This novel and economical method is suitable for scale-up activities.

Symbiotic Catalysis Relay: Molecular Oxygen Activation Catalyzed by Multiple Small Molecules at Ambient Temperature and its Mechanism

the National Natural Science Foundations of China (20772111;20876149;21025206;20832003;20972118;20772093);the “973” Project from the MOST of China (2011CB808600);“the Fundamental Research Funds for the Central Universities”;the Program for New Century Excellent Talents in University (NCET);the Academic Award for Excellent Ph.D. Candidates funded by Ministry of Education of China

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

A series of bulky geometry-constrained iminopyridylpalladium chlorides were developed. The steric environment adjacent to the nitrogen atom in the pyridine rings and diimine parts enhanced the thermal stability of the palladium species. Bulkier groups at the imino group stabilized the palladium species and the corresponding palladium chlorides showed high activities in the coupling reaction of aryl chlorides.

A practical iodine-catalyzed oxidative conversion of aldehydes to nitriles

A simple and efficient method for the direct synthesis of nitriles from aldehydes using ammonium acetate as the nitrogen source has been developed. The reactions were performed with iodine as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant under mild conditions. A variety of aromatic, heteroaromatic, aliphatic and allylic aldehydes could be converted into their corresponding nitriles in good to excellent yields.

Hexachlorocyclotriphosphazene (HCCP)-Mediated Direct Formation of Thioethers and Ethers from Quinazolin-4(3H)-ones

A hexachlorocyclotriphosphazene (HCCP)-mediated direct formation of quinazoline (thio)ethers from quinazolin-4(3H)-ones has been developed. Treatment of quinazolin-4(3H)-ones with HCCP, diisopropylethylamine (DIPEA), and thiophenols resulted in formation of the corresponding 4-arylthioquinazoline derivatives in moderate to excellent yields. This method has also been utilized to prepare 4-aryloxyquinazoline and 4-alkoxyquinazoline derivatives using phenols and sodium alkoxides as the nucleophiles.

Synthesis of a heterogeneous Cu(OAc)2-anchored SBA-15 catalyst and its application in the CuAAC reaction

A novel dinuclear Cu(OAc)2-anchored SBA-15 catalyst was synthesized by simple proton exchange of a carboxyl functionalized mesoporous SBA-15 silica with Cu(OAc)2 in water. XAFS and EPR spectra were utilized to probe its structure. Such a Cu(II) solid material exhibited excellent catalytic activity for the azide–alkyne cycloaddition reaction in water without addition of either reductant or base.

An efficient Pd–NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

Three PEG-functionalized imidazolium salts L1–L3 were designed and prepared from commercially available materials via a simple method. Their corresponding water soluble Pd–NHC catalysts, in situ generated from the imidazolium salts L1–L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki–Heck reactions. The kinetic study revealed that the Pd catalyst derived from the imidazolium salt L1, bearing a pyridine-2-methyl substituent at the N3 atom of the imidazole ring, showed the best catalytic activity. Under the optimal conditions, a wide range of substituted alkenes were achieved in good to excellent yields from various aryl bromides and alkenes with the catalyst TON of up to 10,000.

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone-catalyzed aerobic oxidation reactions via multistep electron transfers with iron(II) phthalocyanine as an electron-transfer mediator

A new biomimetic catalytic oxidation system which employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as the catalyst, molecular oxygen as the terminal oxidant and iron(II) phthalocyanine (FeIIPc) as the electron-transfer mediator has been developed. This system can be applied for oxidative deprotection of PMB ethers, alcohol oxidation, aromatization and α,β-unsaturated aldehyde formation. After immobilizing FeIIPc on multi-walled carbon nanotubes, it can be reused without loss of activity.

One-Pot Synthesis of 4-Aminoquinazolines by Hexamethyldisilazane-Mediated Reaction of Quinazolin-4(3H)-ones with Amines

Abstract Hexamethyldisilazane-mediated reaction of quinazolin-4(3H)-ones with primary amines led to facile formation of 4-aminoquinazolines through tandem silylation and substitution in a single pot. Excellent yields of the products (83–97%) and environmental friendliness (avoiding the use of chlorination reagents) are the advantages of this method.

Unsymmetrical CNN-palladacycles with geometry-constrained iminopyridyl ligands: an efficient precatalyst in Suzuki coupling for accessing 1,1-diarylalkanes from secondary benzylic bromides

We developed a series of unsymmetrical CNN-palladacycles with geometry-constrained iminopyridyl ligands, which were conveniently prepared through a simple one-pot procedure from the corresponding 2-aryl-5,6,7-trihydroquinolin-8-ones. The palladium complexes were fully characterized by 1H and 13C NMR spectroscopy and ESI-mass spectrometry. X-ray analyses of Pd1 to Pd4 have shown their solid structures. Using these CNN-palladacycles as the precatalyst, various secondary benzylic bromides have been successfully coupled with arylboronic acids, affording 1,1-diarylalkanes with high selectivity. A TON of up to 47 000 was achieved. The scale-up reaction further demonstrated the practicality and efficiency of the developed strategy.