A novel one-pot procedure for the stereoselectivesynthesis of α-hydroxy estersfrom ortho esters was developed. Key steps were multi-heteroatom Cope rearrangements of O-acylated N-hydroxy-l-tert-leucinol-derived oxazoline N-oxides leading to α-acyloxy oxazolines and, after methanolysis, to the target molecules in 67−80% yield and 94−98% ee.
Substituent effects in ring-chain tautomerism of the condensation products of non-racemic 1,2-aminoalcohols with aromatic aldehydes
作者:Márta Juhász、László Lázár、Ferenc Fülöp
DOI:10.1016/j.tetasy.2011.11.011
日期:2011.12
at 300 K as three-component (ringcis-open-ringtrans) tautomeric mixtures. The electronic effects of the 2-aryl substituents on the tautomeric equilibria were described by the Hammett equation. Good correlations were found between the equilibrium constants and the Hammett–Brown parameter (σ+) of the substituent X on the 2-phenyl group.