Department of Applied Chemistry, Tokyo University of Science.
Proc Jpn Acad Ser B Phys Biol Sci. 2019;95(3):89-110. doi: 10.2183/pjab.95.009.
Biological homochirality, such as that of l-amino acids, has been a puzzle with regards to the chemical origin of life. Asymmetric autocatalysis is a reaction in which a chiral product acts as an asymmetric catalyst to produce more of itself in the same absolute configuration. 5-Pyrimidyl alkanol was found to act as an asymmetric autocatalyst in the enantioselective addition of diisopropylzinc to pyrimidine-5-carbaldehyde. Asymmetric autocatalysis of 2-alkynyl-5-pyrimidyl alkanol with an extremely low enantiomeric excess of ca. 0.00005% exhibited significant asymmetric amplification to afford the same pyrimidyl alkanol with >99.5% enantiomeric excess and with an increase in the quantity of the same compound. We have employed asymmetric autocatalysis to examine the origin of homochirality. Asymmetric autocatalysis triggered by circularly polarized light, chiral minerals such as quartz, chiral organic crystals composed of achiral compounds gave highly enantioenriched pyrimidyl alkanol with absolute configurations corresponding with those of the chiral triggers. Absolute asymmetric synthesis without the intervention of any chiral factor was achieved. Chiral isotopomers acted as chiral triggers of asymmetric autocatalysis.
生物手性，如 L-氨基酸的手性，一直是生命化学起源的一个谜。不对称自催化是一种反应，其中手性产物作为不对称催化剂，以相同的绝对构型产生更多的自身。在嘧啶-5-甲醛与二异丙基锌的对映选择性加成反应中，发现 5-嘧啶基烷醇可作为不对称自催化剂。具有约 0.00005%极低对映体过量的 2-炔基-5-嘧啶基烷醇表现出显著的不对称放大，以获得具有 >99.5%对映体过量的相同嘧啶基烷醇，并增加相同化合物的数量。我们已经利用不对称自催化来检验手性的起源。手性矿物（如石英）和由非手性化合物组成的手性有机晶体所引发的圆偏振光的不对称自催化，可得到具有与手性触发物相对应的绝对构型的高度富集对映体的嘧啶基烷醇。无需任何手性因素干预即可实现绝对不对称合成。手性同位素对充当不对称自催化的手性触发物。
