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Asymmetric Steering of Oxa Diels–Alder Reactions with Silyloxydienes Employing Proline Esters as Chiral Auxiliary Groups
Author(s) -
Bläser Edwin,
Kolar Patrik,
Fenske Dieter,
Goesmann Hellmut,
Waldmann Herbert
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199901)1999:1<329::aid-ejoc329>3.0.co;2-z
Subject(s) - chemistry , diastereomer , ozonolysis , proline , absolute configuration , chiral auxiliary , stereochemistry , lanthanide , diels–alder reaction , organic chemistry , enantioselective synthesis , amino acid , catalysis , ion , biochemistry
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 δ‐lactones 10 or dihydro‐γ‐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.