Selective mono-fluorination of diols via a cyclic acetal of N,N-diethyl-4-methoxybenzamide

Selective mono-fluorination of 1,2- and 1,3-diols was achieved using N,N-diethyl-4-methoxybenzamide diethyl acetal and Et3N-3HF. The reaction proceeds through a cyclic acetal of the benzamide, and only one hydroxy group was fluorinated and another one was acylated.