One-Pot Synthesis of Functionalized 3-Aryl-1-phenyl-1<i>H</i>-pyrazoles from Hydrazonoyl Chlorides and Acetylenic Esters in the Presence of Ph<sub>3</sub>P
The zwitterionic 1 : 1 intermediates generated by addition of Ph3P to acetylenicesters is trapped by 1‐[(aryl)chloromethylene]‐2‐phenylhydrazines (=N‐phenylarenecarbohydrazonoyl chlorides) to yield functionalized 3‐aryl‐1‐phenyl‐1H‐pyrazoles in good yields.
A copper-promoted aerobic oxidative [3+2] cycloaddition reaction for the synthesis of various substituted pyrazoles from N,N-disubstituted hydrazines with alkynoates in the presence of bases is developed. This work involves a direct C(sp3)–H functionalization and the formation of new C–C/C–N bonds. In this strategy, inexpensive and easily available Cu2O serves as the promoter and air acts as the green