Synthesis of catalytically active ruthenium complexes with a remote chiral lactam as hydrogen-bonding motif

A terminal alkyne was prepared, which is linked by a carbon-carbon bond to a conformationally restricted, U-shaped chiral lactam, that is, more precisely, to carbon atom C7 of 1,5,7-trimethyl-3-azabicyclo[3.3.1]nonan-2-one. The alkyne was connected to various ligands (bipyridine, terpyridine, pybox) by Sonogashira cross-coupling with the respective bromides or triflates. The resulting products were converted into four defined ruthenium complexes (58-94% yield). The complexes contain a catalytically active metal center, which is spatially remote from the hydrogen-bonding motif of the chiral lactam. Preliminary experiments with one of these complexes proved that the complex shows catalytic activity in oxidation reactions and that enantioselectivity is achieved due to substrate coordination to the chiral lactam.