Jimin Xu

Highly efficient synthesis of phenols by copper-catalyzed oxidative hydroxylation of arylboronic acids at room temperature in water.

A general and efficient procedure for the preparation of phenols was developed by copper-catalyzed oxidative hydroxylation of arylboronic acids at room temperature in water.

Carboxylic Acid-Promoted Copper(I)-Catalyzed Azide−Alkyne Cycloaddition

In this article, we proved that all three key steps in the catalytic cycle of CuAAC can proceed in the presence of carboxylic acids and the latter two steps can be promoted significantly by carboxylic acids. Benzoic acid showed the best promotion activity, and the acids with strong chelating ability to Cu(I) ion could not serve for this purpose. Thus, the first carboxylic acid-promoted highly efficient CuAAC was established.

Total synthesis of (-)-cocaine and (-)-ferruginine.

Total synthesis of tropane alkaloids (-)-cocaine and (-)-ferruginine were accomplished in nine steps each and in 55% and 46% overall yields, respectively, starting from the known Betti base derivative (+)-(7aR,10R,12S)-10-(1H-benzotriazol-1-yl)-7a,8,9,10-tetrahydro-12-phenyl-12H-naphtho[1,2-e]pyrrolo[2,1-b][1,3]oxazine. In this novel route, RCM reaction and 1,3-dipolar cycloaddition were employed as key steps for the enantioselective construction of tropane skeleton and the regioselective introduction of 3-bromo-2-isoxazoline ring as masked cis-2,3-disubstituents. To obtain the desired precursor (2S,5R)-2-allyl-5-vinylpyrrolidine for RCM reaction, we developed a general and practical method for the preparation of enantiopure cis-2,5-disubstituted pyrrolidines bearing alkene- and/or alkyne-containing substituents. We also offered two highly efficient pathways for the conversion of the 3-bromo-2-isoxazoline ring into the desired cis-2,3-disubstituted groups in (-)-cocaine and (-)-ferruginine.

Direct ortho-arylation of N-phenacylpyridinium bromide by palladium-catalyzed C-H-bond activation.

A novel palladium catalyzed direct ortho-arylation of N-phenacylpyridinium bromide was developed. The amazing N-phenacyl group regioselectively activates the C-H bond of pyridine and automatically departs from the arylated products. A kinetic isotope effect study proved that the reaction went through a C-H-bond activation pathway and 2,6-diphenylpyridine was produced stepwise from 2-phenylpyridine.

Highly Chemoselective Pd−C Catalytic Hydrodechlorination Leading to the Highly Efficient N-Debenzylation of Benzylamines

In the presence of 1,1,2-trichloroethane, a novel procedure for the Pd-C catalytic N-debenzylation of benzylamines was established. The method proceeded in a synergistic catalytic system and directly gave the products as crystal amine hydrochlorides in practically quantitative yields.

Total synthesis of (+)-epilupinine via an intramolecular nitrile oxide-alkene cycloaddition.

Total synthesis of (+)-epilupinine was accomplished in nine steps and in 48% overall yield, in which INOC was used as the key step for the construction of the quinolizidine skeleton. We found that it was an extremely difficult task to prepare the key intermediates (R)-N-(3-nitropropyl)-2-vinylpiperidine or (R)-(2-vinylpiperid-1-yl)propanal by routine methods. Thus, by using Fukuyamas oxime synthesis, a general method was developed for highly efficient conversion of 3-(N,N-dialkylamino)propanols into 3-(N,N-dialkylamino)propanal oximes without using the corresponding aldehydes.