✦ LIBER ✦

Asymmetric Steering of Oxa Diels–Alder Reactions with Silyloxydienes Employing Proline Esters as Chiral Auxiliary Groups

✍ Scribed by Edwin Bläser; Patrik Kolar; Dieter Fenske; Hellmut Goesmann; Herbert Waldmann

Publisher: John Wiley and Sons
Year: 1999
Tongue: English
Weight: 171 KB
Volume: 1999
Category: Article
ISSN: 1434-193X
DOI: 10.1002/(sici)1099-0690(199901)1999:1<329::aid-ejoc329>3.0.co;2-z

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✦ Synopsis

Chiral aldehydes 4a,b, obtained by the ozonolysis of the dihydro-γ-pyrones 13 with very high diastereomeric ratios (up to 99:1). The absolute configuration of the predominating corresponding N,NЈ-fumaroylbis[(S)-proline esters] 3 react in the presence of lanthanoid chelate complexes Eu(fod) 3 or diastereoisomer of compound 10b was unequivocally determined by X-ray structural analysis. Eu(hfc) 3 with silyloxydienes 7 or 12 to give δ-lactones 10 or [a]