Mixed S/N and S/P/N ligands from carbohydrates: Synthesis and application in palladium-catalyzed allylic alkylation

A modular synthetic approach to bidentate and tridentate imino-thioglycoside ligands is reported. In only 5 steps from the known glucosamine derivative 1, a conveniently functionalized thioglycoside 5 is obtained, which after imination afforded the desired ligands in excellent yields. The tridentate phosphine imine thioglycoside ligand 10 was found to be a highly efficient catalyst precursor for palladium-(0)-catalysed asymmetric alkylation of 1,3-diphenylpropenylacetate (8) with dimethyl malonate. The study of a Pd(II) complex shows that there is an efficient stereochemical control of the sulfur configuration upon coordination to the palladium.

Graphical abstractTridentate P/N/S ligand 10 obtained in only 5 steps from a known glucosamine derivative was shown to be a good catalyst precursor for the palladium-(0)-catalysed asymmetric alkylation of 1,3-diphenylpropenylacetate (8) with dimethyl malonate. The use of only 3.6 mol% of Pd and 5 mol% of 10 afforded the product with high yield and up to 90% ee.Figure optionsDownload full-size imageDownload as PowerPoint slide