Activation of disarmed 2-O-alkoxycarbonylated glycosyl trichloroacetimidates with lanthanide triflates: an efficient approach for the synthesis of 1,2-trans glycosides

Disarmed glycosyl trichloroacetimidates can be activated by Yb(OTf)3 in the synthesis of 1,2-trans glycosides involving primary and secondary acceptors. Concurrent formation of orthoester side products can be avoided by the use of alkoxycarbonyl groups for the protection of the donor 2-hydroxyl.