title: Regioselective acetylation of diols and polyols by acetate catalysis: mechanism and application.
abstract: We propose a principle for H-bonding activation in acylation of hydroxyl groups, where the acylation is activated by the formation of hydrogen bonds between hydroxyl groups and anions. With the guidance of this principle, we demonstrate a method for the selective acylation of carbohydrates. By this method, diols and polyols are regioselectively acetylated in high yields under mild conditions using catalytic amounts of acetate. In comparison to other methods involving reagents such as organotin, organoboron, organosilicon, organobase, and metal salts, this method is more environmentally friendly, convenient, and efficient and is also associated with higher regioselectivity. We have performed a thorough quantum chemical study to decipher the mechanism, which suggests that acetate first forms a dual H-bond complex with a diol, which enables subsequent monoacylation by acetic anhydride under mild conditions. The regioselectivity appears to originate from the inherent structure of the diols and polyols and their specific interactions with the coordinating acetate catalyst.
authors.affiliation: Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry & Chemical Engineering, Huazhong University of Science & Technology , Luoyu Road 1037, Wuhan 430074, People's Republic of China.
authors.forename: Bo
authors.initials: B
authors.lastname: Ren
authors.forename: Martin
authors.initials: M
authors.lastname: Rahm
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Zhang
authors.forename: Yixuan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Hai
authors.initials: H
authors.lastname: Dong