Direct Examination of Extraterrestrial Chirality in Meteorites Using Asymmetric Autocatalysis

Direct Examination of Extraterrestrial Chirality in Meteorites Using Asymmetric Autocatalysis 

We analyzed several organic and inorganic phases identified from the Murchison and Murray meteorites [100] in order to determine whether they contain any possible chirality besides the enantiomeric amino acids [98]. Asymmetric autocatalysis is a method capable of revealing chiral imbalances in various media, therefore, we employed this method as a possible chiral sensor for the meteorites. 

We performed the addition reaction of z-Pr2Zn to pyrimidine-5-carbalde-hyde 11 in the presence of a constituent phase of the meteorite by appropriate treatments. Asymmetric autocatalysis with amplification of chirality gave pyrimidyl alkanol 12 with ee of detectable level. 

On the other hand, the IOM samples from which several percent amounts of organic compounds had been removed by hydrothermolytic treatment (IOM-H) gave results that are in sharp contrast to the above-mentioned meteoritic sample. Here, both (R)- and (S)-pyrimidyl alkanol 12 were obtained equally and indicate the absence of chiral factors in the IOM-H sample, i.e., the results are stochastic. Similar stochastic results were obtained on conducting the asymmetric autocatalysis in the presence of Murchison powders from which all the organic material had been removed by exposure to oxygen plasma. 

The above results are interpreted as indicating the presence of diverse chirality in unknown meteorite organics. 

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