4-Nitrophenyl triflate (1) as well as 4-nitrophenyl nonaflate (2) are excellent perfluoroalkanesulfonyl transfer agents. An important feature of the present method is its chemoselectivity. The aliph. hydroxy function was inert under the reaction conditions studied , and consequently phenols can be selectively triflated in the presence of alc. Frontier MO calcns. were used to rationalize the exptl. results. [on SciFinder (R)]