A general protocol for the synthesis of S-trifluoromethyl S-arylsulfoximine thioglycosides has been reported. This protocol is based on a Pd-catalyzed Migita cross-coupling between o-iodo S-trifluoromethyl S-arylsulfoximines and a broad range of 1-thiosugars. This method gives access to a series of [a

We have discovered a new mode of reactivity of 1-thiosugars in the presence of Cu(II) or Co(II) for a stereoselective O-glycosylation reaction. The process involves the use of a catalytic amount of Cu(acac) 2 or Co(acac) 2 and Ag 2 CO 3 as an oxidant in α,α,α-trifluorotoluene (TFT). Moreover, this protocol turned out to have a broad scope, allowing to prepare a wide range of complex substituted O-glycoside esters in good to excellent yields with an exclusive 1,2-trans-selectivity. The late-stage modification of pharmaceuticals by this method was also demonstrated. To get a closer insight into the reaction mechanism, cyclic voltammetry (CV) was performed.[a] Reactions conditions: procedure (A) with Cu : carboxylic acids 5 (1 equiv), O-acetylated 1-thio-β-D-glucose 1a (1.5 equiv), Cu(acac)2 (5 mol %), Ag2CO3 (3 equiv), TFT [0.1 M] in a sealed tube under argon at 130 °C under microwave irradiation for 15 min. Procedure (B) with Co: carboxylic acids 5 (1 equiv), O-acetylated 1-thio-β-D-glucose 1a (1.5 equiv), Co(acac)2 (5 or 10 mol %), Ag2CO3 (3 equiv), TFT [0.1 M] in a sealed tube under argon at 150 °C for 1 hour under thermal conditions. b yield for the isolated product. c diastereomeric mixture 1:1 calculated by 1 H NMR.