Chapter 29 - Asymmetric Autocatalysis, Absolute Asymmetric Synthesis and Origin of Homochirality of Biomolecules

Abstract

The chapter describes highly enantioselective asymmetric autocatalysis with amplification of ee and asymmetric autocatalysis initiated by chiral substances such as quartz and sodium chlorate. It also describes absolute asymmetric synthesis in conjunction with asymmetric autocatalysis. Chiral 5-pyrimidyl alkanol, 2, 3-quinolyl alkanol, and 5-carbamoyl-3-pyridyl alkanol are highly enantioselective asymmetric autocatalysts for the addition of /-Pr2Zn to pyrimidine-5-carbaldehyde, 1, 3-quinolinecarbaldehyde, and 5-carbamoyl-3- pyridinecarbaldehyde, respectively. Among these, 2-alkynyl -5-pyrimidyl alkanol 2c is a highly efficient asymmetric autocatalyst with >99.5% enantioselectivity. Moreover, asymmetric autocatalysis with amplification of ee from extremely low ee to >99.5% ee is realized by consecutive asymmetric autocatalysis without the need for any other chiral auxiliary. Kinetic analysis of pyrimidyl alkanol suggests that the reaction proceeds via order of the zinc monoalkoxide of pyrimidyl alkanol. Chiral organic compounds with low ee, which are induced by CPL, serve as chiral triggers of the asymmetric autocatalysis. The overall process correlates the chirality of CPL with an organic compound with very high ee.