36837-34-0Relevant academic research and scientific papers
The diaza-Nazarov cyclization involving a 2,3-diaza-pentadienyl cation for the synthesis of polysubstituted pyrazoles
Aegurla, Balakrishna,Peddinti, Rama Krishna
, p. 9643 - 9652 (2017/11/30)
An unprecedented iodine-mediated diaza-Nazarov (DAN) type cyclization for the construction of substituted pyrazoles from easily available starting materials via an enamine-iminium ion intermediate is described. The oxidative cyclization worked under green conditions with remarkable regioselectivity. This one-pot, efficient and operationally simple three-component intramolecular regioselective DAN cyclization displayed a wide range of substrate scope. The dichotomy of reaction pathways has been explored with density functional theory in the gas phase and solution phase. Of the possible 1,5-, 1,6-, and 1,7-electrocyclizations, the DAN cyclization, i.e., the 1,5-pathway offers the lowest activation energy barrier supporting our experimental observations.
A complementary approach to 3,5-substituted pyrazoles with tosylhydrazones and terminal alkynes mediated by TfOH
Liu, Ping,Xu, Qian-Qian,Dong, Chao,Lei, Xinsheng,Lin, Guo-Qiang
supporting information, p. 2087 - 2092 (2012/11/07)
A complementary method for the preparation of 3,5-substituted pyrazoles in moderate to high yields has been explored via TfOH-induced addition of tosylhydrazones to the terminal alkynes. This acid-induced addition procedure might be an operationally safe alternative compared to typical 1,3-dipolar cycloaddition as there is no involvement of diazo compounds.
Facile access to pyrazolines via domino reaction of the Huisgen zwitterions with aziridines
Cui, Sun-Liang,Wang, Jing,Wang, Yan-Guang
, p. 13 - 16 (2008/09/17)
A novel, efficient, and general domino reaction of 2-acylaziridines with the Huisgen zwitterions to furnish 2-pyrazoline rings is described. A possible mechanism for the domino sequence is proposed.
