title: Total synthesis of phenylpropanoid glycoside osmanthuside-B6facilitated by double isomerisation of glucose-rhamnose orthoesters.
abstract: A convenient synthesis of phenylpropanoid glycoside osmanthuside-B6is disclosed. The key steps involved regioselective coumaroylation and rhamnosylation of unprotected phenylethyl-β-d-glucopyranoside to give 2- and 3-O-rhamnosyl orthoester glucopyranosides. Rearrangement of these orthoesters followed by selective removal of their acetyl and allyl groups gave osmanthuside-B6in 22% overall yield. The rearrangement involved a newly discovered glucose-rhamnose orthoester double isomerization process that has the potential to provide a convenient access to many complex phenylpropanoid glycosides. The synthetic route developed is envisioned to serve as a model for the preparation of phenylpropanoid glucosides having a (substituted) cinnamoyl moiety at O-6 and a saccharide moiety at O-3.
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, N1.2 B1-14, Singapore 637459, Singapore. zaher@ntu.edu.sg.
authors.forename: Duc Thinh
authors.initials: DT
authors.lastname: Khong
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, N1.2 B1-14, Singapore 637459, Singapore. zaher@ntu.edu.sg.
authors.forename: Zaher M A
authors.identifier: http://orcid.org/0000-0001-7319-2312
authors.initials: ZM
authors.lastname: Judeh
mesh_terms: D004952:Esters / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry*; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010636:Phenols / Q000138:chemical synthesis* / Q000737:chemistry; D012210:Rhamnose / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D004952:Esters; D006027:Glycosides; D010636:Phenols; C000626227:osmanthuside-B6; D005947:Glucose; D012210:Rhamnose