University Chemistry ›› 2020, Vol. 35 ›› Issue (7): 1-7.doi: 10.3866/PKU.DXHX201912076

Special Issue: 有机化学课程与实验教学

• Chemistry Today • Previous Articles     Next Articles

Mechanism of Semidine Rearrangements

Jiaxi Xu()   

  • Received:2019-12-30 Accepted:2020-01-28 Published:2020-02-24
  • Contact: Jiaxi Xu E-mail:jxxu@mail.buct.edu.cn

Abstract:

Semidines, including ortho-semidines and para-semidines, are generally byproducts in the benzidine rearrangements of N, N'-diarylhydrazines under acidic conditions. Under certain cases, for instance, N, N'-diarylhydrazines with substituted aryl substituents would give o- and p-semidines as major products. The π complex mechanism, and mechanisms involving cyclohexadiene cation intermediates and chloride-bridge-linked dication diradical pairs for the formation of semidines were proposed. However, by referring the data of kinetic isotope effect studies, theoretical and experimental investigations suggest that semidine rearrangements are sigmatropic shifts of pericyclic reactions with configuration-inverted N[1, 3] sigmatropic shift as a key step. Mechanistic investigations and examples of semidine rearrangements are reviewed in this paper.

Key words: Sigmmatropic shift, Rearrangement, N[1, 3] sigmmatropic shift, Semidine, Diarylhydrazine, Configuration inversion

MSC2000: 

  • G64