Exploiting sodium ascorbate as an underutilized and sustainable sacrificial reductant for net reductive pinacol coupling reactions via mechanophotocatalysis

Mechanochemistry can mediate reactions containing components that are poorly soluble in organic solvents, thereby facilitating access to new chemical space. These reagents may also be safer to handle and less costly than analogs used in solution-state reactions, providing secondary tangible benefits. In this study, we report the use of sodium ascorbate as a sacrificial reductant in net reductive pinacol couplings of aromatic aldehydes and ketones driven by mechanophotocatalysis. Sodium ascorbate replaces the sacrificial reductants typically used to deliver these 1,2-diol products (such as DIPEA and the Hantzsch ester). The solvent-minimized protocol returned more consistent results than the solution-state reference reaction, highlighting mechanophotocatalysis as a valuable tool for mediating heterogeneous photochemical reactions. An initial positive result for a reductive amination protocol using ascorbate is also disclosed.