Modular syntheses of chiral and achiral C,N-chelated Pd(II)-pyridinylidenes.

Modular, high-yielding routes to achiral and chiral, C,N-chelated pyridinylidene complexes of Pd(II) have been developed which rely on oxidative addition of either chloropyridinium imines or aldehydes to Pd(0), respectively, and, in the latter case, subsequent Schiff base formation with chiral primary amines. These protocols succinctly circumvent many of the problems currently associated with the synthesis of chelating pyridinylidenes.

Chiral, hemilabile palladium(II) complexes of tridentate oxazolidines, including C2-symmetric "pincers".

Two classes of diastereomerically enriched chiral tridentate ligands incorporating either two oxazolidine and one pyridine ( 1) or two pyridine and one oxazolidine ( 2a-c) donor groups have been made in a high-yielding modular fashion from readily available enantiopure amino alcohols and aldehydes. Both ligand classes readily formed metal complexes via 1:1 reactions with trans-PdCl 2(PhCN) 2. The compounds Pd( 1)Cl 2 and Pd( 2a-c)Cl 2 were formed as mixtures of 3 and 2 diastereomers, respectively, owing to indeterminate absolute configuration at the C (2) position of their constituent oxazolidine rings.