Benzoxaborole Catalyst for Site‐Selective Modification of Polyols

• Published in: European journal of organic chemistry Vol. 2020; no. 11; pp. 1598 - 1602
• Main Authors: Kusano, Shuhei, Miyamoto, Shoto, Matsuoka, Aki, Yamada, Yuji, Ishikawa, Ryuta, Hayashida, Osamu
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 22.03.2020; Wiley Subscription Services, Inc
• Subjects: Benzoxaborole; Benzoylation; Catalysts; Catalytic activity; Chemical synthesis; Chemistry; Chemistry, Organic; cis‐1,2‐Diols; Derivatives; Glycosylation; Hydroxyl groups; Physical Sciences; Polyols; Science & Technology; Selectivity; Site‐selective modification; SUBSTRATE SCOPE; DIOL; ACTIVATION; REGIOSELECTIVE ALKYLATION; ACID; RECOGNITION; BENZOBOROXOLES; ACYLATION; SULFONYLATION; 2-Diols; Benzoxaborole; Glycosylation; Polyols; FUNCTIONALIZATION; cis-1; Site-selective modification
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201901749

The site‐selective modification of polyols bearing several hydroxyl groups without the use of protecting groups remains a significant challenge in synthetic chemistry. To address this problem, novel benzoxaborole derivatives were designed as efficient catalysts for the highly site‐selective and protecting‐group‐free modification of polyols. To identify the effective substituent groups enhancing the catalytic activity and selectivity, a series of benzoxaborole catalysts 1a–k were synthesized. In‐depth analysis for the substituent effect revealed that 1i–k, bearing multiple electron‐withdrawing fluoro‐ and trifluoromethyl groups, exhibited the greatest catalytic activity and selectivity. Moreover, 1i‐catalyzed benzoylation, tosylation, benzylation, and glycosylation of various cis‐1,2‐diol derivatives proceeded with good yield and site‐selective manner. Novel benzoxaborole derivatives were designed as efficient catalysts for the highly site‐selective and protecting‐group‐free modification of polyols, such as carbohydrate. Additionally, the benzoxaborole catalyst could tolerate diverse modifications of polyols, including acylation, sulfonylation, alkylation, and glycosylation.