Preparation of oxetanes by 4-endo trig electrophilic cyclisations of cinnamic alcohols

The reaction of substituted cinnamic alcohols with bis(sym-collidine)bromine(I) hexafluorophosphate was examined. In general no oxetane was obtained when a substituent was fixed on the carboncarbon double bond. However, oxetanes were formed in high yields when two substituents were present in α of the alcohol function.