Stereoselective Syntheses of Pentose Sugars Under Realistic Prebiotic Conditions
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Glycolaldehyde and dl-glyceraldehyde reacted in a water-buffered solution under mildly acidic conditions and in the presence of chiral dipeptide catalysts produced pentose sugars whose configuration is affected by the chirality of the catalyst. The chiral effect was found to vary between catalysts and to be largest for di-valine. Lyxose, arabinose, ribose and xylose are formed in different amounts, whose relative proportions do not change significantly with the varying of conditions. With LL-peptide catalysts, ribose was the only pentose sugar to have a significant D-enantiomeric excess (ee) (≤44%), lyxose displayed an L-ee of ≤66%, arabinose a smaller L-ee of ≤8%, and xylose was about racemic. These data expand our previous findings for tetrose sugars and further substantiate the suggestion that interactions between simple molecules of prebiotic relevance on the early Earth might have included the transfer of chiral asymmetry and advanced molecular evolution.
KeywordsAsymmetric synthesis Pentose sugars Aldol condensation Dipeptide Catalyst
We thank Esther Varon for technical assistance in these studies and Ronald Breslow for reviewing the manuscript. This investigation was supported by grants from the National Aeronautics and Space Administration programs: Astrobiology and Exobiology (SP and AW), Cosmochemistry and Origins of the Solar System (SP).
- Pizzarello S, Cooper GW, Flynn GL (2006) The nature and distribution of the organic material in carbonaceous chondrites and interplanetary dust particles. In: Lauretta D, McSween HY (eds) Meteorites and the early Solar System II. University of Arizona Press, Tucson, pp 625–651Google Scholar