title: Regioselective, borinic acid-catalyzed monoacylation, sulfonylation and alkylation of diols and carbohydrates: expansion of substrate scope and mechanistic studies.
abstract: Synthetic and mechanistic aspects of the diarylborinic acid-catalyzed regioselective monofunctionalization of 1,2- and 1,3-diols are presented. Diarylborinic acid catalysis is shown to be an efficient and general method for monotosylation of pyranoside derivatives bearing three secondary hydroxyl groups (7 examples, 88% average yield). In addition, the scope of the selective acylation, sulfonylation, and alkylation is extended to 1,2- and 1,3-diols not derived from carbohydrates (28 examples); the efficiency, generality, and operational simplicity of this method are competitive with those of state-of-the-art protocols including the broadly applied organotin-catalyzed or -mediated reactions. Mechanistic details of the organoboron-catalyzed processes are explored using competition experiments, kinetics, and catalyst structure-activity relationships. These experiments are consistent with a mechanism in which a tetracoordinate borinate complex reacts with the electrophilic species in the turnover-limiting step of the catalytic cycle.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto ON M5S 3H6, Canada.
authors.forename: Doris
authors.initials: D
authors.lastname: Lee
authors.forename: Caitlin L
authors.initials: CL
authors.lastname: Williamson
authors.forename: Lina
authors.initials: L
authors.lastname: Chan
authors.forename: Mark S
authors.initials: MS
authors.lastname: Taylor
mesh_terms: D000215:Acylation; D000478:Alkylation; D001889:Borinic Acids / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D006018:Glycols / Q000737:chemistry*; D006031:Glycosylation; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism; D013379:Substrate Specificity; D013451:Sulfonic Acids / Q000737:chemistry*
chemical_list: D001889:Borinic Acids; D002241:Carbohydrates; D006018:Glycols; D013451:Sulfonic Acids