Asymmetric cross-coupling of racemic α-bromo esters with aryl Grignard reagents catalyzed by cyclopropane-based bisoxazolines cobalt complexes

作者：Liu, Feipeng; Sian, Qinghua; Mao, Jianyou; Gao, Zidong; Liu, Dan; Liu, Shikuo; Wang, Xueyang; Wang, Yu; Wang, Min; Zhong, Jiangchun^*

来源：Tetrahedron: Asymmetry , 2016, 27(14-15): 663-669.

DOI：10.1016/j.tetasy.2016.05.010

• TRANSITION-METAL-COMPLEXES
• ENANTIOSELECTIVE PROTONATION
• ALKYL-HALIDES
• ACID
• HYDROGENATION
• LIGANDS

Four new cyclopropane-based bisoxazolines were synthesized and applied to cobalt-catalyzed cross-coupling reactions between racemic alpha-bromo esters and aryl Grignard reagents. The reaction afforded a series of chiral alpha-arylalkanoic esters with high yields and good enantioselectivities (up to 93% yield, 92:8 er). This research focuses on the cross-coupling between racemic alpha-bromopropanoate and p-isobutylphenyl Grignard reagent's which provides ibuprofen ester efficiently. Furthermore, ibuprofen ester 7e was transformed into (S) -ibuprofen (99:1 er) via hydrolysis and recrystallization.

• 出版日期2016-8-15
• 单位中国农业大学