The desire to access molecules with three-dimensional structures is of great importance in drug discovery. Two decades of exploration in selective arene saturation have recently culminated in productive Late-Stage Saturation (LSS) strategies.1–6 The Glorius Lab has been developing LSS strategies where complex molecules like drugs can have their aromatic rings reduced, thus increasing the fraction of sp3-atoms, a property which has been shown to correlate with improved drug properties like solubility, selectivity, and metabolic stability. Generally, rhodium catalysts are used under mild conditions without a need for high pressure reactors, although high-pressure hydrogen is used for stubborn reductions or to achieve selectivity. The general mechanism for arene saturation involves the reaction of the rhodium precatalyst with the boron reductant to generate hydrogen gas and heterogeneous rhodium nanoparticles in situ, which directly catalyze the hydrogenation. However, LSS is a general strategy for reducing arenes in complex pharmaceuticals and embraces diverse reaction conditions or mechanisms. For some specific cases, such as indoles and quinolones, can also be reduced by acid-mediated reduction,9 or photocatalyzed-hydrogenation.9,11 This reaction has been demonstrated in a miniaturized format, making it amenable to library synthesis in drug discovery.9,12