[Pd(N,N-chelate)(olefin)] complexes containing chiral nitrogen chelates based on carbohydrates - Enantioselectivity of olefin coordination

Chiral N,N-chelates of formula 6-Me-pyridine-2-CH=N-R (1) and R-N=CH-CH=N-R (2) (R = 6-deoxy-alpha-D-glucoside or 6-deoxy-alpha-D-mannoside residue) a nd their palladium(0) complexes [Pd(N,N-chelate)(olefin)] (I) were prepared . Symmetrical type 2 ligands induced higher enantioselectivity in the coord ination of prochiral olefins. The ability of a type 1 chelate to promote a stereoselective process was also assessed, i.e. dimethylfumarate inserted i nto the Pd-Me bond formed upon methylation of a type I complex with 50% ee. Finally a water-soluble Pd-0 complex was also prepared by deprotecting the alcoholic functions on the sugar residue, and its molecular structure dete rmined through X-ray diffractometry.