Metal nitrates catalysed O-glucosylation using acetyl glucal in organic solvents and ionic liquids: A comparative investigation

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2005-06, Vol.234 (1), p.35-43
• Main Authors: Naik, Prashant U., Nara, Susheel J., Harjani, Jitendra R., Salunkhe, Manikrao M.
• Format: Article
• Language: English
• Subjects: 3,4,6-Tri- O-acetyl- d-glucal; Alcohols; Catalysis; Chemistry; Exact sciences and technology; Ferrier glucosylation; General and physical chemistry; Ionic liquids; Metal nitrates; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2005.02.017

The screening of metal nitrates revealed the ability of Bi(NO 3) 3·5H 2O and Fe(NO 3) 3·9H 2O as catalyst for the Ferrier O-glucosylation using 3,4,6-tri- O-acetyl- d-glucal. The Bi(NO 3) 3·5H 2O-mediated O-glucosylation show substantial solvent dependency and enhanced reaction rate in [bmim][PF 6] than in the conventional organic solvents. Apart from the ambient quality, eco-friendly nature and catalyst economy, the Bi(NO 3) 3·5H 2O/[bmim][PF 6] method offers good yields and high anomeric selectivity, reduced catalyst concentration, reduced reaction time and recyclability of reaction medium. ▪ The Ferrier glucosylation of alcohols with 3,4,6-tri- O-acetyl- d-glucal has been investigated with several metal nitrates and the optimal catalyst is bismuth nitrate pentahydrate (BNP). Good yields of pseudoglycals were also obtained with ferric nitrate nonahydrate (FNN), heightening the catalyst dosage (50 mol%) being required however. The BNP-mediated reactions showed remarkable solvent dependency and in the optimal protocol, the amount of BNP as low as 10 mol% was effective, furnishing excellent yields of O-glucosides with good anomeric selectivity in acetonitrile. A comparison of BNP and FNN in terms of yields and selectivity of the product has been made. In comparison to the reactions in acetonitrile, the catalytic ability of BNP was found to enhance drastically in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF 6].