Haiying Zhan

Highly regioselective C–H bond functionalization: palladium-catalyzed arylation of substituted imidazo[1,2-a]pyridine with aryl chlorides

We have developed an efficient Pd-catalyzed regioselective arylation of substituted imidazo[1,2-a]pyridines with aryl chlorides, which is rarely reported. This methodology has been successfully applied to the synthesis of a variety of substituted imidazo[1,2-a]pyridine core π systems which exhibit a wide range of biological activities in many drugs.

Ruthenium-catalyzed direct C-3 oxidative olefination of imidazo[1,2-a]pyridines

A highly regioselective oxidative olefination of imidazo[1,2-a]pyridines with acrylates has been accomplished in the presence of ruthenium catalysts to form only the C-3 coupling products. The oxidative olefination has provided step economical access to diversely substituted imidazo[1,2-a]pyridine derivatives with excellent C-3 regioselectivity and E-stereoselectivity.

Photocatalytic degradation kinetics and mechanism of phenobarbital in TiO2 aqueous solution

5-Ethyl-5-phenylpyrimidine-2,4,6(1H, 3H, 5H)-trione is an anti-convulsant used to treat disorders of movement, e.g. tremors. This work deals with the transformation of phenobarbital by UV/TiO(2) heterogeneous photocatalysis, to assess the decomposition of the pharmaceutical compound, to identify intermediates, as well as to elucidate some mechanistic details of the degradation. The photocatalytic removal efficiency of 100 μm phenobarbital is about 80% within 60 min, while the degradation efficiency of phenobarbital was better in alkaline solution. The study on contribution of reactive oxidative species (ROSs) has shown that ()OH is responsible for the major degradation of phenobarbital, while the photohole, photoelectrons and the other ROSs have the minor contribution to the degradation. Finally, based on the identification of degradation intermediates, two main photocatalytic degradation pathways have been tentatively proposed, including the hydroxylation and cleavage of pyrimidine ring in the phenobarbital molecule respectively. Certainly, the phenobarbital can be mineralized when the photocatalytic reaction time prolongs.

Ligandless microwave-assisted Pd(OAc)2-catalyzed direct arylation of thiazolo[3,2-b]-1,2,4-triazoles

An efficient microwave-assisted Pd(OAc)2-catalyzed direct arylation of thiazolo[3,2-b]-1,2,4-triazoles with aryl bromides under ligandless conditions has been developed. The method is functional group tolerant and provides rapid access to target compounds in good yields.

Microwave-assisted C–N and C–S bond-forming reactions: an efficient three-component domino sequence for the synthesis of sulfoether-decorated imidazo[1,2-a]pyridines

An efficient and simple microwave-assisted three-component reaction for the formation of imidazo[1,2-a]pyridine derivatives in the presence of F3CCO2H has been described. The three-component reaction of 3-phenylpropiolaldehyde, pyridin-2-amines and thiols gives the desired products in good yields. It represents an efficient approach for the formation of C–N and C–S bonds under microwave irradiation.