Palladium-Catalyzed Asymmetric Trifluoromethylated Allylic Alkylation of Pyrazolones Enabled by α-(Trifluoromethyl)alkenyl Acetates

The first asymmetric trifluoromethylated allylic alkylation of pyrazolones using alpha-(trifluoromethyl)alkenyl acetates as a novel trifluoromethylated allylation reagent is described, affording various functionalized chiral pyrazolones containing a trifluoromethylated allyl substituent in high yields with excellent regio-/enantio-/diastereoselectivities. Mechanistically, the double-bond migration of alpha-(trifluoromethyl)alkenyl acetates in the presence of 1,8-diazabicyclo[5.4.0] undec-7-ene is initial and interesting step. More importantly, this study is of significance in providing a novel and widely applicable trifluoromethyl-containing allylation reagent.

Automated summary

This study describes the first asymmetric trifluoromethylated allylic alkylation of pyrazolones using a novel trifluoromethylated allylation reagent. The reaction affords functionalized chiral pyrazolones with high yields and excellent selectivities. The double-bond migration of alpha-(trifluoromethyl)alkenyl acetates is identified as an initial and interesting step in the mechanism. Additionally, this study is significant in providing a novel and widely applicable trifluoromethyl-containing allylation reagent.