Enantioselective catalysis.: Part 142:: Carbohydrate-derived oxime ethers from functionalised aldehydes and O-β-D-glucopyranosylhydroxylamine -: new C=N ligands stable towards hydrolysis

A new way of linking carbohydrates to phosphorus- or nitrogen-containing aldehydes via oxime ethers is described resulting in novel C=N ligands which are stable towards hydrolysis. Reaction Of O-beta -D-glucopyranosythydroxylamine 2 with 2-diphenylphosphanylbenzaldehyde 3 or pyridine-2-carbaldehyde 4 afforded the oxime ethers O-(beta -D-glucopyranosyl)-2-diphenylphosphanylbenzaldoxime 5 and O-(beta -D-glucopyranosyl)pyridine-2-carbaldoxime 6. After peracetylation of the hydroxyl groups in 5 and 6, the protected sugar derivatives O-(2,3,4,6-tetra-O-acetyl-beta -D-glucopyranosyl)-2-diphenylphosphanylbenzaldoxime 7 and O-(2,3,4,6-tetra-O-acetyl-beta -D-glucopyranosyl)pyridine-2-carbaldoxime 8 were obtained. The molecular structure of 7 was established by X-ray diffraction studies. (C) 2001 Elsevier Science Ltd. All rights reserved.