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Stereochemical Control of Chirally Flexible Phosphepines
Author(s) -
Zalubovskis Raivis,
Fjellander Ester,
Szabó Zoltán,
Moberg Christina
Publication year - 2007
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.200600717
Subject(s) - atropisomer , chemistry , diastereomer , enantiomer , stereochemistry , rhodium , metal , catalysis , medicinal chemistry , organic chemistry
The barriers to interconversion of the two enantiomeric atropisomers of 6‐methoxy‐6,7‐dihydro‐5 H ‐dibenzo[ c , e ]phosphepine and that of the diastereomeric forms of 6‐(–)‐menthoxy‐6,7‐dihydro‐3 H ‐dibenzo[ c , e ]phosphepine were determined by NMR spectroscopical methods to be 19.3 and 18.5 kcal mol –1 , respectively, at 298 K. The ratio of the atropisomers was shown to depend on the group bound to phosphorus. Only complexes with two homochiral ligands bound to the each metal center were obtained upon reaction with [Rh(COD) 2 ] + BF 4 – . The Rh complexes catalyzed the hydrogenation of α‐acetamidocinnamate. The major isomer of6‐(–)‐menthoxy‐6,7‐dihydro‐5 H ‐dibenzo[ c , e ]phosphepinewas found to exhibit higher activity but to afford a product with lower ee than its diastereomer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)