The CBS reduction used to be the only general solution to achieve catalytic asymmetric reduction of simple unfunctionalized ketones. In the 1990’s, Noyori’s group discovered that Ru(II)-diphosphine-diamine complexes were capable of catalyzing asymmetric hydrogenation of simple ketones. This hydrogenation is highly chemoselective that ketones (and aldehydes) can be reduced in the presence of olefins. The catalytic activity of these catalysts is also very high. Depending on the substrate, the catalytic turnover (TON) exceeds 100,000.