942274-96-6Relevant articles and documents
Preparation of new axially chiral bridged 2,2′-bipyridines and pyridyl monooxazolines (pymox). Evaluation in copper(i)-catalyzed enantioselective cyclopropanation
Bouet, Alexis,Heller, Barbara,Papamicael, Cyril,Dupas, Georges,Oudeyer, Sylvain,Marsais, Francis,Levacher, Vincent
, p. 1397 - 1404 (2007/12/27)
This work reports the synthesis of new axially chiral bridged 2,2′-bipyridines 1 and pyridylmonooxazolines (pymox) 2. The potential of these new axially chiral N,N-ligands was evaluated in asymmetric catalytic cyclopropanation of styrene derivatives 22a-c with diazoesters 21a,b. While 2,2′-bipyridines 1a-c afforded the corresponding cyclopropanes 23a-f in up to 65% ee, pymoxs 2a-e gave somewhat lower enantioselectivities (up to 53% ee). Both classes of ligands produced trans-cyclopropanes 23a-f as the major isomer, although with modest diasteroselectivities (56: 44 to 78: 22). A structure-stereoselectivity relationship study of ligands 1 and 2 identified the chiral biaryl axis as being mostly responsible for the enantioselective performances of these ligands. The Royal Society of Chemistry.
