G. Arrhenius et al., GLYCOLONITRILE OLIGOMERIZATION - STRUCTURE OF ISOLATED OXAZOLINES, POTENTIAL HETEROCYCLES ON THE EARLY EARTH, Journal of organic chemistry, 62(16), 1997, pp. 5522-5525
A study of glycolonitrile polymerization has led to the isolation and
characterization of two 2,5-dihydro-4-aminooxazoles, 4 and 5. Previous
reports have misassigned these structures as s-triazines or pyrimidin
es, X-ray diffraction analysis of crystals of 4 and an acetylated oxaz
ole derivative of 5 (6) confirm the proposed structures. Ab initio com
putations are used to assess the relative thermodynamic stability of t
hree trimer isomers (an s-triazine, an aminohydroxypyrimidine, and an
aminooxazoline), and the results indicate that 4 is a novel kinetic pr
oduct. Mechanistic considerations rationalize kinetic oxazole formatio
n over the more customary triazine or pyrimidine trimers.