One-Pot Consecutive Reductive Amination Synthesis of Pharmaceuticals: From Biobased Glycolaldehyde to Hydroxychloroquine

Reductive amination plays a paramount role in the synthesis of amines. It is often proposed as a more ecofriendly synthesis process than the traditional S(N)2-type reactions of amines as it avoids toxic alkylation reagents such as alkyl halides. This work demonstrates the versatility of the reductive amination reaction via the synthesis of hydroxychloroquine (HCQ), one of the most renowned pharmaceuticals during this coronavirus pandemic. The novel green synthesis strategy is based on three consecutive reductive amination reactions conducted in a one-pot system, avoiding intermediary purification steps. Furthermore, a biobased C-2 platform molecule, glycolaldehyde, was selected as a starting reagent. The newly developed reductive amination pathway was appraised using the CHEM21 Green Metric toolkit and compared with the commercially operating method.