title: HClO4-silica-catalysed regioselective opening of benzylidene acetals and its application towards regioselective HO-4 glycosylation of benzylidene acetals in one-pot.
abstract: Here we report a high-yielding method for the regioselective reductive ring opening of 4,6-O-benzylidene acetals of hexapyranosides using inexpensive and robust HClO4-SiO2 as the acidic catalyst and triethylsilane as the hydride donor. Under the optimized condition, gluco- and mannopyranosides give the respective 6-O-benzyl derivative in good to excellent yields while the corresponding galactopyranoside gives the corresponding 6-O-benzyl derivative in lower yield. As the optimized condition involves acidic catalyst, we also successfully developed further application of the present method for the tandem regioselective opening and glycosylation in one-pot.
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India; Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India.
authors.forename: Saidulu
authors.initials: S
authors.lastname: Dara
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India; Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India.
authors.forename: Varma
authors.initials: V
authors.lastname: Saikam
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India.
authors.forename: Mahipal
authors.initials: M
authors.lastname: Yadav
authors.affiliation: Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India. Electronic address: ppsingh@iiim.res.in.
authors.forename: Parvinder Pal
authors.initials: PP
authors.lastname: Singh
authors.affiliation: Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India; Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Jammu 180 001, India. Electronic address: ram@iiim.res.in.
authors.forename: Ram A
authors.initials: RA
authors.lastname: Vishwakarma
mesh_terms: D000080:Acetals / Q000138:chemical synthesis / Q000737:chemistry*; D001597:Benzylidene Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002236:Carbohydrate Conformation; D002384:Catalysis; D006031:Glycosylation; D010472:Perchlorates / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000080:Acetals; D001597:Benzylidene Compounds; D010472:Perchlorates; D012822:Silicon Dioxide
keywords: Glycosylation; HClO(4)–SiO(2); One-pot; Reductive ring-opening; Regioselective