Chapter 1 - Asymmetric Autocatalysis and the Origins of Homochirality of Organic Compounds. An Overview

Abstract

Asymmetric autocatalysis is a reaction in which a chiral product acts as a chiral catalyst for its own production. 5-Pyrimidyl alkanol acts as an asymmetric autocatalyst with amplification of chirality in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. 2-Alkynyl-5-pyrimidyl alkanol with an extremely low enantiomeric excess (ca. 0.00005% ee) acts as an asymmetric autocatalyst to afford the same alkanol with significantly amplified ee (>99.5%). Theories of the origins of homochirality have been examined by using asymmetric autocatalysis with amplification of ee. Circularly polarized light, chiral inorganic crystals, such as quartz, chiral organic crystals composed of achiral compounds, and spontaneous absolute asymmetric synthesis, have been considered as candidates for the origins of chirality. It was found that asymmetric autocatalysis is triggered by these origins of chirality, affording the pyrimidyl alkanol with high ee and with the corresponding absolute configurations to the chirality of the chiral triggers. Chiral isotopomers of carbon (C13/C12), oxygen (O18/O16), and hydrogen (D/H) were also found to trigger asymmetric autocatalysis. Asymmetric autocatalysis enables us to discriminate the chirality of cryptochiral compounds.