Studies on the Dehydrogenative Polymerizations of Monolignol β‐Glycosides. Part 1. Syntheses of Monolignol β‐glycosides, (E)‐Isoconiferin, (E)‐Isosyringin, and (E)‐Triandrin

Abstract

(E)‐4‐O‐Acetyl coniferyl alcohol was synthesized by the reduction of (E)‐4‐O‐acetyl ferulic acid with sodium borohydride and N,N‐dimethylchloromethylenium chloride in 80.2% yield. The glycosylation of (E)‐4‐O‐acetyl coniferyl alcohol with trichloroacetimidoyl 2,3,4,6‐tetra‐O‐pivaloyl‐α‐D‐glucopyranoside in the presence of BF₃-Et₂O in anhydrous CH₂Cl₂, followed by deacylation gave (E)‐isoconiferin in high yield. This synthetic method could be applied to the syntheses of other monolignol β‐glycosides. As a result, (E)‐isoconiferin, (E)‐isosyringin, and (E)‐triandrin were synthesized from vanillin, syringaldehyde, and p‐hydroxybenzaldehyde, respectively, by five reaction steps in high overall yield.

Keywords:

• Lignin
• DHP
• isoconiferin
• isosyringin
• triandrin
• imidate method