Chemistry of sugars without protecting groups 1. regioselective esterification of the anomeric hydroxyl of lactose maltose and glucose
Plusquellec, D.; Foulleau, F.; Bertho, F.; Lefeuvre, M.; Brown, E.
Tetrahedron 42(9): 2457-2468
ISSN/ISBN: 0040-4020 Accession: 004940489
Treatment of acyl chlorides 4 with mercaptothiazoline, mercaptobenzothiazole, p-nitrophenol and 8-hydroxyquinoline in the presence of Et3N, afforded high yields of the corresponding reactive amides 5a-h, S-thioesters 6e-h and aryl esters 7e-h and 8a-h, respectively. The esters 6e-h, 7e-h and 8e-h reacted with excess .beta.-lactose in pyridine, to give the corresponding .beta.-esters 9e-h resulting from esterification of the anomeric hydroxyl of the sugar. The amides 5c, f-h gave the .alpha.-lactosyl esters 9c, f-h. The amide 5e and the esters 8b, c, e, reacted with .beta.-maltose, thus affording the corresponding .beta.-maltosyl esters 10b, c, e, whereas the compounds 8a-e reacted with .beta.-glucose, yielding the corresponding .beta.-glucosyl esters 11a-e. This appears to be one of the very few selective chemical modifications of sugars known, which do not involve the toilsome protection-deprotection methology. The now commercially available maltosyl and glucosyl esters 10e and 11d-e are new non-ionic, and water-soluble detergents which could be used for studies of cell membrane proteins.