Asymmetric catalysis is one of the most active branches in modern organic chemistry research, and asymmetric catalytic reactions are considered to be the most efficient methods for synthesizing chiral substances. The principle is to convert achiral raw materials into chiral products by using chiral catalysts. Therefore, the chiral ligand complexed with the catalyst is a key factor affecting the enantioselectivity of the reaction.

Bidentate oxazoline chiral ligands (Figure 1) are a new type of highly efficient chiral ligands developed by Professor Ye Longwu’s research group. They can complex with transition metals such as copper and zinc to catalyze a series of asymmetric reactions. Compared with phenyl-substituted BOX ligands, this type of ligand has greater steric hindrance and is expected to exhibit higher enantioselectivity in certain asymmetric catalytic reactions. What’s more noteworthy is that Professor Ye’s research group developed a new synthesis method, and bidentate oxazoline ligands can be efficiently prepared under mild conditions.

Figure 1 New large sterically hindered bidentate oxazoline chiral ligand

application
This type of ligand has been successfully used in two types of transition metal-catalyzed asymmetric reactions (Figure 2).

In the zinc-catalyzed asymmetric [4+3] cyclization reaction of acetylenic ether substrates and isoxazoles, a series of 2H-Azepines compounds were synthesized with high enantioselectivity through the 6π electrocyclization pathway, using the L2 complex The chiral target product was obtained with an ER value as high as 97:3. [1]
In the copper-catalyzed asymmetric tandem amination and cyclopropanation of azide-alkynamides, a series of cyclopropane derivatives were obtained with high enantioselectivity through the α-imine copper carbene intermediate pathway, using L1 complex. The chiral target product was obtained with an ER value as high as 98:2. [2]
For the above two types of reactions, using traditional BOX-type ligands, the target products can only be obtained with moderate er values. This reflects the significant advantages of the new large sterically hindered BOX ligand.

Figure 2 Application of new large sterically hindered bidentate oxazoline ligands in asymmetric catalysis

Teacher profile
Ye Longwu is a professor at the School of Chemistry and Chemical Engineering of Xiamen University and the leader of the project. From 1999 to 2003, he studied at the Department of Chemistry, Zhejiang University (supervisor: Academician Akira Aso), and from 2003 to 2008, he studied for a doctoral degree at the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (supervisor: Academician Tang Yong). From 2008 to 2011, he engaged in postdoctoral research at The Scripps Research Institute and the University of California, Santa Barbara (UCSB) in the United States. In 2011, he was funded by Xiamen University Jiageng Chemical Platform and entered the School of Chemistry and Chemical Engineering of Xiamen University. The research direction is the synthesis methodology based on alkyne transformation and its application in the synthesis of functional heterocyclic molecules. Received the Fujian Provincial Science Fund for Outstanding Youth (2015), the National Natural Science Foundation of China "Outstanding Youth Fund" (2016), the Thieme Chemistry Journals Award (2016), the Ministry of Education Young Yangtze River Scholar (2017), and the Fujian Provincial Youth Top Talents (2017) , first prize of Xiamen University’s “Tian Zhaowu Interdisciplinary Award” (2019), etc.

Product name：

(4S,4'S)-2,2'-(Propane-2,2-diyl)bis(4-([1,1':3',1''-terphenyl]-5'-yl)-4,5-dihydrooxazole)

CAS：2489182-84-3

Item number：9189538

Product name：

(4S,4'S)-2,2'-(Propane-2,2-diyl)bis(4-(3,5-di(naphthalen-2-yl)phenyl)-4,5-dihydrooxazole)

CAS：2410445-32-6

Item number：9189539