Asymmetric fluoroallylboration of aldehydes

Contrary to previous reports, the homologation of benzyloxydifluorovinyllithium with bulky chiral iodomethylboronates readily provides a series of chiral γ,γ-difluoroallylboronates. Asymmetric fluoroallylboration of aldehydes with a 2-phenylbornane-2,3-diol-derived reagent provides gem-difluorinated homoallyl alcohols in good yields and 77-95% ee. Preparation of a chiral α-pyrone in >99% ee has also been described.