Synthesis of 2-Alkenyl-2H-indazoles from 2-(2-Carbonylmethyl)-2H-indazoles

Mei-Huey Lin, Kung-Yu Liang, Chang-Hsien Tsai, Yu-Chun Chen, Hung-Chang Hsiao, Yi-Syuan Li, Chung-Hao Chen, Hau-Chun Wu
2016 Molecules  
A procedure has been developed for synthesis of 2-alkenyl-2H-indazoles starting from 2-(2-carbonylmethyl)-2H-indazoles, which are prepared by gallium/aluminium-and aluminium-mediated, direct, regioselective alkylation of indazoles with α-bromocarbonyl compounds. The structure of 3-(2H-indazol-2-yl)-2H-chromen-2-one was proven by X-ray crystallography. The styrene-and coumarin-2H-indazoles produced by using the new method were found to have interesting fluorescence properties. Molecules 2016,
more » ... Molecules 2016, 21, 238 2 of 11 thermodynamic alkylation products predominate in reactions run under most basic conditions [18] . Fortunately, the results of recent studies in this area show that 2H-indazoles are generated through gallium/aluminium-and aluminium-mediated direct regioselective alkylation reactions of an indazole with α-bromocarbonyl compounds [19] . Below, we describe observations made in an investigation in which this new alkylation procedure was applied to the synthesis of a variety of 2-alkenyl-2H-indazoles.
doi:10.3390/molecules21020238 pmid:26907234 fatcat:y74veunsuzdqboj3w35bkxy5ze