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The Stereodynamics of 5,5’‐Disubstituted BIPHEPs
Author(s) -
Maier Frank,
Trapp Oliver
Publication year - 2013
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.22125
Subject(s) - chemistry , enantioselective synthesis , chirality (physics) , catalysis , high performance liquid chromatography , stereochemistry , medicinal chemistry , organic chemistry , chiral symmetry , physics , quantum mechanics , nambu–jona lasinio model , quark
We investigated the stereodynamics of 5,5’‐substituted tropos BIPHEP ligands (2,2’‐bis(diphenylphosphino)‐biphenyls) by enantioselective dynamic high‐performance liquid chromatography (DHPLC) to elucidate the influence of the substitution pattern and electronics of the substituents (methyl, methoxy, and hydroxyl groups). By temperature‐dependent dynamic HPLC measurements the activation parameters Δ G ╪ , Δ H ╪ , and Δ S ╪ could be determined with high precision, revealing that the activation barrier of these 5,5’‐substituted BIPHEP ligands ranges in a narrow band between 87.8 and 93.0 kJ mol –1 , making them highly attractive as deracemizable dynamic chiral ligands in asymmetric catalysis . Interestingly, the activation parameters are highly influenced by a hydroxyl or methoxy group in the 5,5’‐position of the BIPHEP ligands. Chirality 25:126–132, 2013 . © 2012 Wiley Periodicals, Inc.