Asymmetric Autocatalysis and the Origin of Homochirality

Asymmetric autocatalysis is a reaction in which chiral product acts as chiral catalyst for its own production. Pyrimdin-5-yl-iso-propylcarbinol (pyrimidyl alkanol) was found to be a highly efficient asymmetric autocatalyst in the enantioselective addition of diisopropyl zinc to pyrimidine-5-carbaldehyde to produce more of itself (Soai reaction). The process is the automultiplicaion, i.e ., catalytic self-replication, of a chiral compound. Pyrimidyl alkanol with extremely low enantiomeric excess (ee) automultiplies and is amplified during three consecutive asymmetric autocatalyses to reach >99.5% ee. By using asymmetric autocatalysis, the origin of homochirality has been examined. Circularly polarized light, inorganic chiral crystals such as quartz, enantiotopic surface of achiral inorganic chiral such as gypsum, chiral crystals of achiral organic compounds, chiral compounds of isotope (hydrogen, carbon, oxygen, nitrogen) substitution, acting as chiral initiators in asymmetric autocatalysis, can be correlated to the highly enantioenriched products. Spontaneous absolute asymmetric synthesis was achieved without the intervention of any chiral factor.