Mi-Na Zhao

The Fe(ii)-catalyzed cyclization of 2H-azirines and N,N-dimethylformamide as an amine source has been developed for the synthesis of 1-methyl-4,5-diaryl-1H-imidazoles.

An iodine-mediated oxidative [4+1] cyclization of enamines with TMSN₃ for the synthesis of 2,5-disubstituted imidazole-4-carboxylic derivatives has been developed. The mechanistic studies revealed that the reaction proceeds through a sequential removal of two nitrogen atoms from TMSN₃. The synthetic utility was further demonstrated with a gram-scale reaction and various derivatization transformations of the products.

A novel and efficient iron-catalyzed cycloaddition reaction using readily available 2,3-diaryl-2H-azirines and primary amides is reported. A wide range of trisubstituted oxazoles could be achieved in good yields with good functional group compatibility. In this transformation, two C–N bonds were cleaed and new C–N and C–O bonds were formed.

An IBX-mediated selected oxidative cyclization of N-hydroxyalkyl enamines was developed. Through this strategy, a variety of 2,3-disubstituted pyrroles and pyridines were produced in good selectivity involving oxidation of alcohol, followed by condensation of aldehyde and α-C of enamines. Furthermore, this metal-free method has several advantages, including the use of environment-friendly reagents, broad substrate scope, mild reaction conditions and high efficiency.

A Rh(III)-catalyzed regioselective intermolecular oxa-Pauson–Khand reaction of arylboronic acids, alkynes and CO for the synthesis of butenolides has been developed. The multi-step reaction proceeded smoothly in the presence of [RhCp*Cl₂]₂ catalyst, NaOAc base and CH₃OH additive. The reaction used readily available starting materials, tolerated various functional groups, and afforded valuable butenolides in good yields with high regioselectivity.