Ruthenium (II) complexes with C2- and C1-symmetric bis-(+)-camphopyrazole ligands and their evaluation in catalytic transfer hydrogenation of aldehydes

•The synthesis of two new chiral bis-(+)-camphopyrazole ligands is reported.•Five piano-stool ruthenium(II) complexes with camphopyrazole ligands were obtained.•The Ru(II) complexes catalyze the transfer hydrogenation of aldehydes from iPrOH.•The system in iPrOH/K2CO3 affords moderate yields of the desired alcohol product.•The TH in isopropanol is more selective than using HCOOH/NEt3 as hydrogen source.