Novel bis(oxazoline) ligands derived from camphoric acid for Cu-catalyzed asymmetric cyclopropanation

Recent Applications of Oxazoline-Containing Ligands in Asymmetric Catalysis

“…Ligand 151b afforded the highest enantiomeric excess of 29% and was subsequently applied in the cyclopropanation of 1,1-diphenylethene with diazoacetate, resulting in an enantiomeric excess of 81%. 130 Ligands derived from tartaric acid have been synthesized by Barros and applied in the enantioselective addition of diethylzinc to chalcone, with the phenylglycinol-derived ligand 152 affording the best enantiomeric excess of 53% (Scheme 1.85). 131 Scheme 1.83 Bolm has developed a range of C 2 -symmetric and C 1symmetric bis(oxazoline) containing ligands 153 for application in a range of asymmetric metal-catalyzed transformations.…”

“…Ligand 151b afforded the highest enantiomeric excess of 29% and was subsequently applied in the cyclopropanation of 1,1-diphenylethene with diazoacetate, resulting in an enantiomeric excess of 81% …”

Recent Applications of C 1-Symmetric Bis(oxazoline)-Containing Ligands in Asymmetric Catalysis

“…In 2005, You applied novel C 1 -symmetric ligand 79, which is derived from camphoric acid in the asymmetric cyclopropanation of styrene (3) and 1,1-diphenylethylene (63a) (Scheme 25). 41 The ligands provided poor levels of enantioselectivity for the conversion of styrene (up to 29% ee) although an enantiomeric excess of 81% (S) was obtained for the cyclopropanation of 1,1-diphenylethylene (63a) in 71% yield with ligand 79c. In 2006, Gade also reported the synthesis and application of a range of C 1 -symmetric bis(oxazoline) ligands ( Figure 13).…”