Preparation of some D-glucofuranosides from unprotected D-glucose

Abstract

O-Glycosidation of 3-(4-methoxyphenyl) propyl alcohol, benzyl alcohol and vanillin with totally unprotected D-glucose, performed in a heterogeneous media and promoted by anhydrous ferric chloride, afforded competent D-glucofuranosides as the major and D-glucopyranosides as the minor products of the reaction.

Direct One-Pot Synthesis of Nucleosides from Unprotected or 5-O-Monoprotected d-Ribose

“…It is worth noting that several protecting group-free strategies to synthesize O -glycosides have been reported typically operating under heavily acidic conditions and date back to the Fischer glycosylation . Modern examples typically employ Lewis acids but are hampered by the need to use stoichiometric or excessive quantities of the often toxic acid as well as long reaction times and high temperature . Only a handful of examples describe direct O- glycosylation under mild or organocatalytic conditions, but none provide any insight on amenability to nucleoside synthesis.…”

Direct Glycosylation of Unprotected and Unactivated Carbohydrates under Mild Conditions

“…Also, methods have been developed to deploy unprotected and unactivated carbohydrates in direct glycosidation processes. These transformations are associated with high reaction temperatures and/or the deployment of strong bases, strong acids, or Lewis acids as catalysts. During our ongoing studies on the application of ligand-exchange mediated C–C bond formation processes, we observed substantial amounts of products derived from acetalization.…”

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

“…The reaction proceeds chemoselective at the anomeric position. More recent examples typically use Lewis acids [ 29 – 34 ] or microwave irradiation [ 35 – 36 ] to accelerate the reaction. However, shortcomings still include the need to use stoichiometric or excessive quantities of the often toxic acid as well as long reaction times, high temperature, and almost a complete lack of stereochemical control [ 37 – 38 ].…”