The timing of the initial collision between the South and North China blocks constraining from the sediments in the eastern Sichuan Basin.

In this study, detrital zircon U-Pb geochronology, trace element and Hf isotopic compositional data from the Early-Middle Triassic clastic rocks in the eastern Sichuan Basin were obtained to distinguish the sediment provenance and constrain the timing of the initial collision between the South China and North China blocks. Detrital zircons from the Early Triassic Feixianguan Formation clastic rocks yield one major age peak at 2476 Ma and three minor age peaks at 1886, 802 and 304 Ma. These detrital zircons may be derived from the South China Block. Detrital zircons from the Early Triassic Jialingjiang Formation clastic rocks yield multiple age peaks at 979, 856, 392 and 269 Ma, indicating a mixed sediment provenance from the South China Block and Qinling Orogenic Belt. This is the first appearance of the detritus with the Qinling Orogenic Belt affinity in the eastern Sichuan Basin. Detrital zircons from the Middle Triassic Leikoupo Formation clastic rocks yield two centralized age peaks at 447 and ca. 245 Ma. These zircons may mainly be derived from the Qinling Orogenic Belt. The results indicate an abrupt change in the detrital zircon U-Pb provenance from the South China Block to the Qinling Orogenic Belt during the Early-Middle Triassic. Integrating the provenance change and other geological characteristics, we suggest that the initial collision in the eastern Qinling Orogenic Belt occurred in the Early Triassic.

Copper(I) acetate-catalyzed azide-alkyne cycloaddition for highly efficient preparation of 1-(pyridin-2-yl)-1,2,3-triazoles.

A highly efficient copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) of 6-substituted tetrazolo[1,5-a]pyridines was developed for the preparation of 1-(pyridin-2-yl)-1,2,3-triazoles by simply using copper(I) acetate as a catalyst. The in situ formed HOAc played important dual roles and an activation of 2-azidopyridine-copper(I) complex was observed.

Total syntheses of (-)-hanishin, (-)-longamide B, and (-)-longamide B methyl ester via a novel preparation of N-substituted pyrrole-2-carboxylates [corrected].

A novel preparation of N-substituted pyrrole-2-carboxylates has been developed based upon 1,3-dipolar cycloaddition and a conventional hydrogenolysis. By using this method as the key step, total syntheses of natural alkaloids (-)-hanishin, (-)-longamide [corrected] B, and (-)-longamide [corrected] B methyl ester were accomplished in the highest overall yields, respectively.

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.