Synthesis of a novel C 2-symmetric bis-oxazoline (=bis[4,5-dihydrooxazole]) and its application as chiral ligand in asymmetric transition metal catalysis

摘要

The new C _2-symmetric bis-oxazoline (=bis[4,5-dihydrooxazole]) 2 with a chiral trans-(2R,3R)-2,3-bis(3,5-diphenylphenyl)cyclopropylidene (=trans-(2R,3R)-2,3-bis([1,1′: 3′,1″-terphenyl]-5′-yl) cyclopropylidene) backbone was efficiently synthesized (Scheme). All synthetic steps were easy to perform and led to the desired product in good overall yields. Compound 2 was tested and compared as ligand in several enantioselective catalytic reactions such as palladium(0)-catalyzed enantioselective allylic alkylations and copper(I)-catalyzed enantioselective cyclopropanations and aziridinations.