Phosphoramidite-based photoresponsive ligands displaying multifold transfer of chirality in dynamic enantioselective metal catalysis

Abstract

The transfer and amplification of chirality in biological and artificial systems is a fundamental process that allows for a dynamic control of structure and function. Only a few responsive systems harness the dynamic transfer of chirality and can act as photoswitchable chiral inductors. Here we demonstrate that photoresponsive phosphoramidite ligands based on a chiral biaryl-substituted molecular switch can be used to alter the activity and invert the stereoselectivity of a copper-catalysed asymmetric conjugate addition. The phosphoramidites were obtained as pairs of diastereoisomers, each displaying a distinct catalytic activity and stereoselectivity as a result of the light-controlled matched–mismatched interaction between the fixed chirality at the phosphorus atom and the dynamic chirality of the switch. The result is an elegant balance of two competing catalysts, of which the complementary catalytic performance is tunable via light, which takes advantage of the internal dynamic transfer of chirality on reversible alkene photoisomerization. This discovery paves the way for the future development of more complex chirality-dependent photoresponsive and multitasking catalysts. [Figure not available: see fulltext.].