Synthesis of a new chiral nonracemic C(2)-symmetric 2,2'-bipyridyl ligand and its application in copper(I)-catalyzed enantioselective cyclopropanation reactions.
An efficient synthesis of a low molecular weight, chiral nonracemic and C(2)-symmetric bipyridyl ligand is reported. The ligand was prepared using a catalytic asymmetric dihydroxylation reaction of a pyrindine as a key step. The ligand was evaluated in the asymmetric copper(I)-catalyzed cyclopropanation reactions of a series of alkenes and diazoesters. Very high diastereoselectivities and enantioselectivities were observed (>95:5 dr and up to 99% ee). These are the highest reported stereoselectivities for a chiral bipyridyl ligand. [structure: see text]
Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6.
Michael P A
MP
Lyle
Peter D
PD
Wilson