In the next step, the Si–OH (silanol) group, acting as a Brønsted acid, donates a proton to the electrophilic keto group (C1) of the glucose to convert it into the enol form (Intermediate-V). This is followed by an intramolecular 1,2 carbon backbone rearrangement, leading to the formation of mannose (Intermediate-VII). Finally, the hydroxyl group at C5
donates the proton to C1, converting the keto group into a hydroxyl group, and forms the ring mannose.