Exploiting an underutilised sustainable sacrificial reductant for net reductive mechanophotocatalysis reactions

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 analogues used in solution-state analogue reactions, providing secondary tangible benefits. Herein, we report the use of sodium ascorbate as a sacri-ficial 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-minimised 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.