109846-11-9Relevant academic research and scientific papers
An efficient one-pot synthesis of 3,5-diaryl-4-bromopyrazoles by 1,3-dipolar cycloaddition of in situ generated diazo compounds and 1-bromoalk-1-ynes
Sha, Qiang,Wei, Yunyang
, p. 413 - 420 (2013/03/14)
A simple, highly efficient, one-pot synthesis of 3,5-di-aryl-4- bromopyrazoles via 1,3-dipolar cycloaddition of diazo compounds and alkynyl bromides has been developed. The diazo compounds and alkynyl bromides were generated in situ from tosylhydrazones and gem-dibromoalkenes, respectively. When ketone-derived hydrazones were used, 3,5-diaryl-4-bromo-3H-pyrazoles were obtained and the isomerization products 3,5-diaryl-4-bromo-1H-pyrazoles were formed when using aldehyde-derived hydrazones. The reaction system exhibited high regioselectivity and good functional group tolerance. Both electron-rich and electron-deficient-substituents on the aromatic ring of the hydrazones or the gem-dibromoalkenes gave desired products in moderate to good yields (67-86%). Georg Thieme Verlag Stuttgart - New York.
