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Schlagwörter:
ORGANIC-SYNTHESIS; N-GLYOXYLOYL-(2R)-BORNANE-10,2-SULTAM; ALDEHYDES; CATALYSIS; CHEMISTRY
Chemistry; asymmetric synthesis; chiral auxiliaries; cycloadditions; lanthanides; delta-lactones;
Zusammenfassung:
Chiral aldehydes 4a,b, obtained by the ozonolysis of the corresponding N,N'-fumaroylbis[(S)-proline esters] 3 react in the presence of lanthanoid chelate complexes Eu(fod)(3) or Eu(hfc)(3) with silyloxydienes 7 or 12 to give delta-lactones 10 or dihydro-gamma-pyrones 13 with very high diastereomeric ratios (up to 99:1). The absolute configuration of the predominating diastereoisomer of compound 10b was unequivocally determined by X-ray structural analysis.
