Identify the major product of the following reaction sequence: (i) MeOH / H ^+ (ii) HIO ₄ (iii) NaBH ₄ ?

Step-by-step solution

The given starting material is D-erythrose, an aldotetrose. Step (i): Reaction with MeOH / H ^+ D-erythrose undergoes intramolecular cyclization where the - OH group at C4 attacks the aldehyde group at C1 to form a 5-membered hemiacetal ring (erythrofuranose). In the presence of acidic methanol, the anomeric hydroxyl group is converted to a methoxy group, forming methyl erythrofuranoside. The ring consists of an oxygen atom bonded to C1 and C4. C1 is bonded to - OMe , C2 and C3 have - OH groups, and C4 is a - CH ₂-