ALKYL 2,2,2-TRIFLUOROETHANESULFONATES (TRESYLATES) - ELIMINATION-ADDITION VS BIMOLECULAR NUCLEOPHILIC-SUBSTITUTION IN REACTIONS WITH NUCLEOPHILES IN AQUEOUS-MEDIA

Alkyl 2,2,2-trifluoroethanesulfonate esters (tresylates), ROSO(2)CH(2) CF(3), react with aqueous base (pH greater than or equal to 9) to give the (alkoxysulfonyl)acetic acid, ROSO(2)CH(2)COOH; with the further a ddition of either a primary or secondary amine or of an alkanethiol, t he product is the either the corresponding amide, ROSO(2)CH(2)C(O)NR(1 )R(2), or a mixture in which the ketene dithioacetal, ROSO(2)CH=C(SR(1 ))(2), or the thioorthoester, ROSO(2)CH(2)C(SR(1))(3), may predominate . Kinetic and product studies are consistent with the following: (a) t he reaction of tresylates with water is the normal sulfonic ester hydr olysis and (b) reaction with hydroxide is an (E1cB)(rev) process with loss of HF to yield the alkyl 2,2-difluoroethenesulfonate, ROSO(2)CH=C F2, which rapidly yields the observed products. Benzyl 2,2,2-trifluoro ethyl sulfone reacts analogously. The relationship between these obser vation with small molecules and those of earlier workers with tresyl a garose is discussed.