Synthesis and Application of β‐Alkynyl‐γ,γ‐Difluoroallylboronates for Metal‐Free Allylation of Aldehydes in Water

β‐Alkynyl substituted γ,γ‐difluoroallyl‐boronates were prepared via defluorination under basic condition. Allylation reaction of aldehydes with gem‐difluoroallylboronates under metal‐free condition in water was developed. As the sole solvent, water dramatically improved the efficiency of the reaction, and afforded the desired products in 48–92% yields. The corresponding difluorinated alcohols were smoothly transformed into the 3,3‐difluoro‐4‐methylene‐3,4‐dihydro‐2H‐pyran derivatives in the presence of gold catalyst.