FeCl₃ mediated arylidenation of carbohydrates

• Published in: Carbohydrate research Vol. 346; no. 5; pp. 534 - 539
• Main Authors: Basu, Nabamita, Maity, Sajal K, Roy, Soumik, Singha, Shuvendu, Ghosh, Rina
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 01.04.2011; Elsevier
• Subjects: Acetals - chemistry; acetic anhydride; acetylation; benzaldehyde; Benzaldehydes - chemistry; Biochemistry & Molecular Biology; Carbohydrate Sequence; Catalysis; cellobiose; Chemistry; Chemistry, Applied; Chemistry, Organic; Chlorides - chemistry; ferric chloride; Ferric Compounds - chemistry; glycosides; Glycosides - chemistry; lactose; Lewis Acids - chemistry; Life Sciences & Biomedicine; Magnetic Resonance Spectroscopy; maltose; Molecular Structure; monosaccharides; Physical Sciences; pyridines; Science & Technology; Thioglycosides - chemistry; Lewis acid; FeCl3; ACID; C-GLYCOSYLATION; CATALYST; FERRIC-CHLORIDE; REPEATING UNIT; Benzylidenation; POT ACETALATION-ACETYLATION; BENZYLIDENE ACETALS; EFFICIENT; DERIVATIVES; Arylidenation; Catalyzed; POLYSACCHARIDE
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2011.01.003

Glycosides and thioglycosides based on monosaccharides in reaction with benzaldehyde dimethylacetal or p-methoxybenzaldehyde dimethyl acetal undergo FeCl₃-catalyzed (20mol%) regioselective 4,6-O-arylidenation producing the corresponding acetals in high yields. FeCl₃ also mediates acetalation of glycosides and thioglycosides of cellobiose, maltose, and lactose affording the corresponding 4′,6′-O-benzylidene acetals, which were isolated after their acetylation in situ with acetic anhydride and pyridine. The combined yields (two steps) of these final products are also high (61–84%). The procedure is applicable to a wide variety of functional groups including –OBn.