A Catalytic One-Step Process for the Chemo- and Regioselective Acylation of Monosaccharides

• Published in: Journal of the American Chemical Society Vol. 129; no. 42; pp. 12890 - 12895
• Main Authors: Kawabata, Takeo, Muramatsu, Wataru, Nishio, Tadashi, Shibata, Takeshi, Schedel, Hartmut
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 24.10.2007; Amer Chemical Soc
• Subjects: Carbohydrate Conformation; Carbohydrates - chemistry; Catalysis; Chemistry; Chemistry, Multidisciplinary; Chemistry, Organic - methods; Hydrogen Bonding; Hydrolysis; Models, Chemical; Molecular Structure; Monosaccharides - chemistry; Physical Sciences; Pyrans - chemistry; Science & Technology; Solvents - chemistry; Stereoisomerism; ALCOHOLS; ANALOGS; KINETIC RESOLUTION; AMINO-ACIDS; DMAP; NUCLEOPHILIC CATALYST; 4-DIALKYLAMINOPYRIDINES; DERIVATIVES
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja074882e

An organocatalytic method for the chemo- and regioselective acylation of monosaccharides has been developed. Treatment of octyl β-d-glucopyranoside with isobutyric anhydride in the presence of 10 mol % of a C 2-symmetric chiral 4-pyrrolidinopyridine catalyst (1) at −50 °C gave the 4-O-isobutyryl derivative as the sole product in 98% yield. Thus, chemoselective acylation, favoring a secondary hydroxyl group in the presence of a free primary hydroxyl group, and regioselective acylation, favoring one of three secondary hydroxyl groups, took place with perfect selectivity. A competitive acylation between octyl β-d-glucopyranoside and a primary alcohol (2-phenylethanol) with 1.1 equiv of isobutyric anhydride in the presence of 1 gave the 4-O-isobutyrate of octyl β-d-glucopyranoside with 99% regioselectivity in 98% yield, which indicates that acylation of the secondary hydroxyl group at C(4) of the carbohydrate proceeds in an accelerative manner. A possible mechanism, involving multiple hydrogen-bonding between 1 and the monosaccharide, is proposed for the chemo- and regioselective acylation.