Synthesis and structural characterization of bis[(4S,5R)-4-methoxycarbonyl-5-methyl-1,3-oxazolidine]copper(II) dichloride and bis[(4S,5R)-4-methoxycarbonyl-5-methyl-2-oxazoline]-[(4S,5R)-4-methoxycarbonyl-5-methyl-1,3-oxazolidine]ruthenium(III) trichlorid

In the reaction of N,N′-methylenebis[(4S,5R)-4-methoxycarbonyl-5-methyloxazolidine] (1) with CuCl2 or RuCl3 in alcoholic solvents novel complexes, bis[(4S,5R)-4-methoxycarbonyl-5-methyl-1,3-oxazolidine]copper(II) dichloride (2) and bis[(4S,5R)-4-methoxycarbonyl-5-methyl-2-oxazoline]-(4S,5R)-4-methoxycarbonyl-5-methyl-1,3-oxazolidineruthenium(III) trichloride (3), respectively, were isolated and fully characterized by X-ray crystallography. In these reactions, which occurred under mild conditions, ligand 1 was cleaved at the bridging aminal position and degraded to (4S,5R)-4-methoxycarbonyl-5-methyl-1,3-oxazolidine 5. The trigonal bipyramidal Cu complex 3 contains two such oxazolidine ligands coordinated in different ways. One is bonded in a monodentate fashion via the nitrogen atom of the five-membered ring, the other binds as a bidentate ligand, additionally using the carbonyl oxygen of the ester group. In the octahedral Ru complex 4 there are one oxazolidine ligand 5 and two oxazoline ligands 6. Thus, in the synthesis of 4 the carbon atom between oxygen and nitrogen in the oxazolidine ring was partly oxidized from the half-aminal status to the carboxamide status.