In Situ generation of difluoromethyl diazomethane for [3+2] cycloadditions with alkynes
1Enamine Ltd. Matrosova 23, 01103 Kyiv (Ukraine) http://www.enamine.net. Pavel.Mykhailiuk@gmail.com, Pavel.Mykhailiuk@mail.enamine.net.
Abstract:
A novel approach to agrochemically important difluoromethyl-substituted pyrazoles has been developed based on the elusive reagent CF2 HCHN2 , which was synthesized (generated in situ) for the first time and employed in [3+2] cycloaddition reactions with alkynes. The reaction is extremely practical as it is a one-pot process, does not require a catalyst or the isolation of the potentially toxic and explosive gaseous intermediate, and proceeds in a common solvent, namely chloroform, in air. The reaction is also scalable and allows for the preparation of the target pyrazoles on gram scale.
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