Boronic Acid-Catalyzed Final-Stage Site-Selective Acylation for the Total Syntheses of <i>O</i>-3′-Acyl Bisabolol β-D-Fucopyranoside Natural Products and Their Analogues

Abstract

The first concise total syntheses of O-3′-senecioyl α-bisabolol β-D-fucopyranoside (4a) and O-3′isovaleroyl α-bisabolol β-D-fucopyranoside (4b) were achieved through final-stage site-selective acylation via the activation of cis-vicinal diols by imidazole-containing boronic acid catalysts as a key step. This synthetic method was also effective for the syntheses of unnatural analogues with modified acyl side chains or carbohydrate moiety.

Emergent Organoboron Acid Catalysts

“…Since these reports, a number of groups have developed the use of boric acid, − borinic acids, − or boronic acids − as catalysts for esterification and amidation reactions, including applications in peptide synthesis, ,, the total synthesis of natural products, and the synthesis of active pharmaceutical ingredients . A few noteworthy examples are highlighted here, focusing on unique catalyst systems and mechanistic analyses.…”