Synthesis of Ynone Trifluoroborates toward Functionalized Pyrazoles

The synthesis of a range of novel ynone trifluoroborates has been achieved, in a two-pot process from propargylic alcohols. These alkynes have been subsequently used in the formation of a range of pyrazole trifluoroborate salts via cyclization with hydrazines. The products are generated with high levels of regiocontrol and in excellent yields and represent versatile synthetic intermediates.