The use of a [4 + 2] cycloaddition reaction for the preparation of a series of 'tethered' Ru(II)-diamine and aminoalcohol complexes.

A series of catalysts have been prepared for use in the asymmetric transfer hydrogenation of ketones. The complexes were prepared using a [4 + 2] cycloaddition reaction at a key step in the reaction sequence. This provides a means for the synthesis of catalysts with modifications at specific sites.