Diverse catalytic systems for nitrogen-heterocycle formation from O-acyl ketoximes

O-Acyl ketoximes has been proven to be versatile building blocks for practical construction of Nheterocycles.In the last few years,diverse catalytic systems have been discovered to enable efficient transformations of O-acyl ketoximes to a range of nitrogen-heterocycles.Herein,we summarized our recent examples of novel nitrogen-heterocycle formation with new function findings of O-acyl ketoximes through facile aerobic copper catalysis,metal-free N–O bond activation,multi-component assembly,and bis-annulations.From the green chemistry perspective,these works represent efficient methods with high atom economy,high selectivity,and minimized chemical waste.These findings also complement well to the previous mainly copper-based catalytic systems and more importantly enrich the oxime chemistry in organic synthesis.

Carbon Tetrabromide/Triphenylphosphine-Activated Beck- mann Rearrangement of Ketoximes for Synthesis of Amides

An efficient Beckrnann rearrangement of ketoximes was developed using carbon tetrabromide/triphenylphos- phine as an organocatalyst without addition of any acids or metals. The reaction showed good functional group tol- erance and gave various amides in moderate to good yields.

Iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates toward 2,4,6-trisubstituted pyrimidines

An iron-catalyzed[4+2]annulation of amidines with α,β-unsaturated ketoxime acetates is described.This strategy employs amidines as CN units and provides a new protocol for the construction of 2,4,6-trisubstituted pyrimidines under batch and continuous flow conditions in moderate to good yields,exhibiting good functional group tolerance,scalability and operational simplicity.

Cu-Catalyzed Cascade Cyclization of Ketoxime Acetates and Alkynals Enabling Synthesis of Acylpyrroles

A facile copper-based catalytic system has been developed to enable efficient cyclization of methylketoximes and alkynals.This protocol provides a viable entry to synthetically and pharmaceutically useful 2-acylpyrroles with a broad range of compatible functionalities.Mechanistically,a key acyl migration is probably involved that leads to the formation of N-acyl pyrroles or otherwise NH pyrroles by further hydrolysis.More importantly,the present reaction system also gives an opportunity to realize three-component pyrrole assembly by simple addition of carboxylic acid.

^(14)N ENDOR Study on Bis(2-Hydroxylphenyl Ketoxime)-^(63)Cu(Ⅱ) Complex

The ENDOR spectrum of 14N-63Cu-HAP complex in DMSO/EtOH （5:1） freezing solution at 20 K has been studied using orientational selective method in this paper. The anisotropic superhyperfine coupling tensor and qusdrupole coupling tensor of ligand 14N nucleus, and the superhyperfine coupling tensor of various 1H nuclei have been measured precisely. Comparing the superhyperfine coupling tensor of 14N-nucleus with previous work shows that the analytical method of spectrum is reasonable and the data are reliable in our previous work.