O‐Galactosylation of Diphenolic Compounds Using Boc Activation: A Convenient Chemical Synthesis

• Published in: ChemistrySelect (Weinheim) Vol. 6; no. 33; pp. 8919 - 8922
• Main Authors: Rajendran, Divya, Bhagavathsingh, Jebasingh
• Format: Journal Article
• Language: English
• Published: 07.09.2021
• Subjects: Carbohydrates; Dopamine; Dopamine glycosides; Fluorescein; glycosyl donor; Glycosylation; L-DOPA
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.202102564

Herein we report the convenient synthesis of O‐galactosylation of diphenolic systems such as Dopamine, L‐DOPA, and Fluorescein by the reaction of Boc‐activated diphenols with α‐bromoacetogalactose in the presence of AgOTf as a promoter and MS 3 Å as an acid scavenger. The Boc protected amine and diphenolic hydroxyl group using t‐butyl dicarbonate facilitates the formation of galactosylated products in the two steps such as Boc‐activation and followed by galactosylation. The protection of C‐terminal carboxylic acid is essential to isolate the β‐ isomer of L‐DOPA glycoside under the same condition. The Boc‐activation of the hydroxyl group in diphenols enhances the nucleophilicity of glycosyl acceptor and the corresponding yields of 72–84 % as β‐isomer through the formation of oxocarbenium intermediate. A convenient synthetic methodology for the galactosylation of diphenolic systems. The Boc‐ activation on the hydroxyl group of diphenols yield the β‐isomer of O‐glycosylated product using AgOTf as a Lewis acid catalyst. It is an alternate method for the synthesis of glycosides of polyphenols.