Asymmetric cyclopropanation in protic media conducted by chiral bis(hydroxymethyl-dihydrooxazolyl)pyridine–ruthenium catalysts
Abstract
Cyclopropanation of styrene with diazoacetates, performed in aqueous/organic biphasic media or homogeneous alcoholic media in the combination of toluene by using chiral bis(hydroxymethyldihydrooxazolyl)pyridine–ruthenium catalyst, resulted in high enantiomeric excess up to 96–97% and trans∶cis stereoselectivity to 97∶3.