10.1002/chem.202001514
Chemistry - A European Journal
COMMUNICATION
show superior catalytic performance with regard to activity and
enantioselectivity, implicating the possible occurrence of an
early form of selection on the primitive Earth. We also observed
the enantiomerically pure crystallization of single enantiomers
thereby opening a plausible pathway for the origin of symmetry
breaking, leading to homochirality. In addition to the access to
substituted aldehydes shown in this work, which seems
necessary for compartmentalization to form cellular structures,
also the formation of the canonical amino acids is plausible. Due
to the similarity to established organocatalysts, many prebiotic
functionalizations via organocatalysis are conceivable, making
these catalysts promising candidates for the ongoing endeavors
to elucidate the origin of life.
Acknowledgements
We acknowledge financial support from the Ludwig-Maximilians-
University Munich, the Max-Planck-Society (Max-Planck-Fellow
Research Group Origins of Life), the VolkswagenStiftung
(Initiating Molecular Life) the Deutsche Forschungsgemeinschaft
DFG (INST 86/1807-1 FUGG, the SFB 235 (Emergence of Life),
and the Cluster of Excellence ORIGINS). We thank Dr. Peter
Mayer for the X-ray structure analysis.
Figure 1. Reaction monitoring of the -cyanomethylation of n-propanal with in-
situ 1H-NMR kinetic measurements. The reaction was performed in DMSO
with 2,6-lutidine under aerobic conditions.
Further, we crystallized several imidazolidine-4-thiones (1b, 1h,
1m, 1p) out of their racemic solution and were pleased to
observe an enantiomerically pure crystal for 1b ((2R,5S)-5-ethyl-
2-methylimidazolidine-4-thione) (Supporting Information Figure
S13, Table S9). In contrast to the formation of a racemic
compound, this conglomerate can lead to spontaneous
resolution, a phenomenon which is comprehensively proposed
as a plausible hypothesis for the origin of molecular chirality.[23]
This feature is rather rare as most of the organocatalysts studied
so far, including nearly all of the proteinogenic amino acids,
crystallize as racemic compounds.[24]
Conflict of interest
The authors declare no conflict of interest.
Keywords: aldehydes • alkylation • organocatalysis • origin of
life • photocatalysis
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imidazolidine-4-thione 1k by preparative chiral HPLC and
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In summary, we identified
a
class of prebiotic
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