Stimuli responsive asymmetric catalysis by triggered pseudo-enantiomeric proligand release

Complex stimuli responsive systems are the basis for molecular machines and computing. A dual psuedo-enantiomer system was conceived, where the combination of two 'switch-on' asymmetric catalytic cycles could be selectively triggered to afford an enantioenriched product. Two pseudo-enantiomeric proligands were designed and synthesised for selective activation by fluoride and alkaline phosphatase. The proligands were firstly incorporated into single proligand systems, and then into a dual proligand system, where enantioselectivity of up to 98 : 2 was achieved in the reduction of prochiral ketone following external stimulation. Two 'switch-on' asymmetric catalytic cycles combined in one system, allowing for enantiocontrol via allosteric activation of pseudo-enantiomeric proligands and a ruthenium pre-catalyst.