Absolute Asymmetric Synthesis: A Commentary

Absolute asymmetric synthesis, i.e., the formation of enantiomerically enriched products from achiral precursors without the intervention of chiral chemical reagents or catalysts, is in practice unavoidable on statistical grounds alone. That random chance, combined with suitable amplification mechanisms, might ultimately account for biomolecular homochirality in Nature was recognized more than a century ago. Soai and collaborators have recently developed an asymmetric autocatalysis reaction that is capable of amplifying a tiny enantiomeric excess of far below 1% to yield a nearly enantiopure product. Although there is no easy way to tell the difference between an asymmetric autocatalysis reaction initiated by the tiny enantiomeric excess due to random chance and one initiated by minuscule quantities of unidentified chiral impurities, it is nevertheless all but certain that the Soai reaction is capable of producing optically active compounds by an absolute asymmetric synthesis, starting from nominally achiral reagents free of chiral contaminants and run under achiral conditions, e.g., without the intervention of chiral physical forces.