Abstract
Arylhydrazones of 2-bromobenzaldehydes and its analogs are cyclized in PEG-400 at 110 °C in the presence of a catalytic amount of copper powder along with NaOtBu to give 1-aryl-1H-indazole derivatives in good yields.
GRAPHICAL ABSTRACT
![](/cms/asset/46022359-e180-47d4-a999-f446a996a261/lsyc_a_614714_o_uf0001.gif)
ACKNOWLEDGMENT
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (2011-0005123).
Notes
a Reaction conditions: 1a (0.5 mmol), copper catalyst (0.05 mmol), base (1 mmol), solvent (5 mL), 110 °C, under N2.
a Reaction conditions: 1 (0.5 mmol), Cu powder (0.05 mmol), NaO t Bu (1 mmol), PEG-400 (3 mL), 110 °C, under N2.