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Synthesis of Enantiopure Tricarbonyl(indan‐1,2‐dione)chromium
Author(s) -
Leinweber Dirk,
Weidner Ingo,
Wilhelm René,
Wartchow Rudolf,
Butenschön Holger
Publication year - 2005
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.200500527
Subject(s) - chemistry , enantiopure drug , enantioselective synthesis , tetrafluoroborate , enantiomer , chromium , substituent , absolute configuration , acetal , ketone , stereochemistry , medicinal chemistry , organic chemistry , ionic liquid , catalysis
A multistep synthesis of the planar chiral tricarbonyl(η 6 ‐indan‐1,2‐dione)chromium, based on acetal protection of the keto groups, is presented. Since common deacetalization procedures failed, an oxidative deprotection with triphenylcarbenium tetrafluoroborate was used. Tricarbonyl(η 6 ‐indan‐1,2‐dione)chromium is regarded as a potential precursor for dianionic oxy‐Cope rearrangements upon alkenyllithium diaddition. As an unexpected side product in the synthesis, an indan‐1,2‐dione complex with a triphenylmethyl substituent at C‐3 was obtained. Attempts directed towards the formation of enantiomerically pure material include the first reported investigation into an enantioselective ketone reduction with two methoxy substituents present in the α position. Although enantiomeric excesses of up to 84.5 % were achieved, the chemical yields decreased with increasing ee . A classical resolution was therefore undertaken, giving access to the enantiomerically pure title compound (99.4 % ee ). The absolute configuration was verified by an X‐ray structure analysis of an intermediate. First experiments concerning the alkenyllithium addition showed that a single addition is possible while a second one does not occur, presumably due to enolate formation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)