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Diastereomeric Enols and Enol Derivatives of 8‐Fluoro‐5,11‐dihydro‐10 H ‐dibenzo[ a , d ]cyclohepten‐10‐one with a Chiral 11‐Substituent
Author(s) -
Compernolle Frans,
Toppet Suzanne,
Brossette Thierry,
Mao Hua,
Koukni Mohamed,
Kozlecki Tomasz,
Medaer Bart,
Guillaume Michel,
Lang Yolande,
Leurs Stef,
Hoornaert Georges J.
Publication year - 2006
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/ejoc.200500796
Subject(s) - chemistry , diastereomer , enol , epimer , substituent , aldol condensation , conformational isomerism , stereochemistry , ring flip , aldol reaction , ring (chemistry) , medicinal chemistry , organic chemistry , molecule , catalysis
Abstract Aldol condensation of 8‐fluoro‐5,11‐dihydro‐10 H ‐dibenzo[ a , d ]cyclohepten‐10‐one and (4 S )‐2,2‐dimethyl‐1,3‐dioxolane‐4‐carbaldehyde provides access to the corresponding ( E , Z )‐α,β‐unsaturated ketones with a (4 R )‐chiral 11‐substituent. Subsequent hydrogenation affords a mixture of (11 R )/(11 S )‐epimeric ketones, which undergoes base‐catalysed equilibration resulting in selective crystallisation of the (11 R ) epimer. The enol intermediate and acyclic enol derivatives are shown to exist as two slowly interconverting conformers with a high inversion barrier of the 10,11‐disubstituted ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)