Having successfully applied our training strategy to R1 and R2, we extended it to model the acid-catalyzed glycoside bond formation between α-trichloroacetate and i -PrOH in explicit DCM, R3 (Fig. ). Glycosylation is a key step in carbohydrate synthesis, involving a glycosyl donor (electrophile) and a glycosyl acceptor (nucleophile, Fig. ). However, controlling its stereoselectivity remains a synthetic challenge. This is due to the continuum of mechanistic pathways available, from concerted S N 2 to stepwise S N 1-type, involving a transient oxocarbenium intermediate, or S N i mechanism, involving a contact ion pair (Fig. ). These pathways have been explored both experimentally 66 and computationally and several factors have been found to influence stereoselectivity, such as the nature of the leaving group, substituents, as well as temperature and solvent.