Practically Perfect Asymmetric Autocatalysis with Amplification of Chirality

Practically Perfect Asymmetric Autocatalysis with Amplification of Chirality 

The next investigation focused on the substituent effect at the pyrimidine ring, especially at the 2-position. The asymmetric autocatalysis in the addition reaction of z-P Zn to pyrimidine-5-carbaldehyde was examined using enantiomerically enriched (S)-2-methyl-l-(5-pyrimidyl)-propan-l-ol 10. The treatment of the corresponding 2-methylpyrimidine-5-carbaldehyde 9 with z-P Zn in the presence of autocatalyst 10 with 99.5% ee resulted in highly 

Obtained alkanol was used as an Asymmetric Autocatalyst for the next round. 

12 was 99% and the ee was 99.5%. Thus, 2-alkynylpyrimidyl alkanol 12 served as a near perfect asymmetric autocatalyst [63]. During these ten consecutive asymmetric autocatalyses, (S)-12 has automultiplied by a factor of ca. 60 000 000, without any decrease in enantioenrichment. 

During these three consecutive asymmetric autocatalyses, the initial major (S)-enantiomer of 12 automultiplied by a factor of ca. 630000 whereas the initially minor (Jt)-enantiomer of 12 automultiplied by less than 1,000 (Fig. 2). The tiny enantiomeric imbalance of ca. 0.00005% ee corresponds to only a few molecules of difference in the number of enantiomeric 12 in an almost racemic mixture of ca. 5 000000 molecules of (S)-12 and ca. 5 000000 molecules of (it)-12. 

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