37944-54-0Relevant academic research and scientific papers
One-pot synthesis of pyrazoles through a four-step cascade sequence
Hao, Lu,Hong, Jun-Jie,Zhu, Jun,Zhan, Zhuang-Ping
supporting information, p. 5715 - 5720 (2013/06/04)
A one-pot synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence, including FeCl 3-catalyzed propargylic substitution, aza-Meyer-Schuster rearrangement, base-mediated 6πelectrocyclization, and thermal [1,5] sigmatropic shift. In this reaction, the 3,4,5- and 1,3,5-pyrazoles are produced selectively according to different substituents in the starting alcohols. A one-pot recipe: The synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence (see figure), and are produced selectively according to different substituents in the starting alcohols.
Reactions of Five-Membered Mesoionic Heterocycles with o-Quinonoid Compounds, V. 1,3-Oxazolium-5-olates and 1,3-Thiazolium-5-olates
Friedrichsen, Willy,Schwarz, Ingo,Epe, Bernd,Hesse, Karl-Friedrich
, p. 622 - 631 (2007/10/02)
1,3-Oxazolium-5-olates (1) and 1,3-thiazolium-5-olates (11) react with o-benzoquinones (3) and α-naphthoquinone to give adducts (4, 5, 6, 15) which can formally be derived from ketene valence tautomers of 1 and 11. 9,10-Phenanthrenequinone and 1a yield a compound (10) which possibly results from an initially formed adduct (7) with subsequent loss of CO2.Consistent with this view is a product (14) of the reaction between 9,10-phenanthrenequinone and 11.The structure of 14 has been determined by X-ray crystallography. - Keywords: o-Quinonoid Compounds, Mesoionic Heterocycles
