Regioselective cycloaddition of trifluorodiazoethane with electron-deficient allenic esters and ketones: access to CF3-substituted pyrazolines and pyrazoles.
A highly regioselective cycloaddition procedure of electron-deficient allenes with trifluorodiazoethane (CF3CHN2) is described. In absence of bases, the reaction proceeded smoothly to give 5-(trifluoromethyl)pyrazolines, whereas the utility of Et3N led to the formation of 3-(trifluoromethyl)pyrazoles.
Department of Chemistry, Key Laboratory of Systems Bioengineering (the Ministry of Education), Tianjin University and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072, P. R. China.
Fa-Guang
FG
Zhang
Yi
Y
Wei
Yu-Ping
YP
Yi
Jing
J
Nie
Jun-An
JA
Ma
D001391:Azo Compounds / Q000737:chemistry*; D061565:Cycloaddition Reaction; D004583:Electrons; D004952:Esters; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis* / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D001391:Azo Compounds; D004952:Esters; D006845:Hydrocarbons, Fluorinated; D007659:Ketones; D011720:Pyrazoles