Difluoromethylenation of Alkynes: Streamlined Access to Allyl Difluorides

ABSTRACT A direct difluoromethylenation of alkynes has been developed using HF/pyridine as a dual acidic and fluorinating medium. The reaction proceeds via in situ generation of a primary oxocarbenium ion from formaldehyde, enabling efficient formation of two C(sp 3 )─F bonds and one C(sp 2 )═C(sp 2 ) bond in a single step without the need for pre‐functionalized reagents. This strategy offers a concise route to allyl difluorides as a complementary approach to incorporate difluoromethylene motifs into complex molecular frameworks. Additional spectroscopic and computational investigations provide insights into this mechanism.