Selectfluor-promoted fluorination of piperidinyl olefins

A simple and straightforward synthesis of 1-substituted-4-aryl-5-fluoro-1,2,3,6-tetrahydropyridine (3) or 1-substituted 4-diarylmethanoyl-4-fluoropiperidine (6) by the treatment of piperidinyl exo- or endo-olefin with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate (Selectfluor) is reported. Two transformations from endo-olefin 1 to allylic fluoride 3 and from exo-olefin 2 to fluorohydrin 6 proceed via allylic fluorination and fluorohydroxylation in moderate yields. It presents two novel reactions promoted by Selectfluor and broadens the scope of application.