Enantioselective Insertion of Carbenoids into N-H Bonds Catalyzed by Chiral Bicyclo Bisoxazoline Copper(I) Complexes

International audienceChiral copper(I)-bicyclobisoxazoline complexes were found to catalyse the insertion of α-diazocarbonyl compounds into N-H bonds of aniline derivatives. The insertion reactions proceeded with high yields (78-99%) and enantioselectivities of up to 81% for the different α-diazopropionates. A predominant effect of the nature and the position of the substituents on the enantiocontrol of the reaction was observe

Synthesis of Diastereomeric Bis(oxazoline) Ligands Derived from (S,S)-1,1′-Bis(4-isopropyloxazolin-2-yl)ferrocene

Starting from (S,S)-1,1′-bis(4-isopropyloxazolin-2-yl)ferrocene, all possible 2-trimethylsilyl- and 2,2′-di(trimethylsilyl)-substituted diastereoisomers, potential bisoxazoline ligands for use in asymmetric catalysis, were synthesised by selective lithiation followed by addition of trimethylsilyl chloride. Access to the (S,S,R p,R p)-diastereoisomer was achieved following diastereoselective introduction of two deuterium-blocking groups and utilisation of the high k H/k D value for lithiation, methodology that was also applied to the synthesis of a related 2,2′-di(diphenylmethanol)bisoxazoline ligand.</jats:p

Synthesis of alternating metallocopolymers by chiral recognition

International audienceWe report the synthesis of chiral enantiopure polytopic bridging ligands, which may lead to the formation of metallosupramolecular polymers with zinc (II) as metal linker. We show that chiral C2‐symmetric bisoxazoline ligands are useful moieties to efficiently generate heterochiral complexes and thus polymeric entities. The corresponding metallopolymers were further characterized by powder X‐ray diffraction (PXRD) to obtain information on the level of crystallinity of our different metallopolymers

Catalytic enantioselective synthesis of quaternary carbon stereocentres.

Quaternary carbon stereocentres-carbon atoms to which four distinct carbon substituents are attached-are common features of molecules found in nature. However, before recent advances in chemical catalysis, there were few methods of constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for the synthesis of single stereoisomers of such organic molecules. This progress now makes it possible to incorporate quaternary stereocentres selectively in many organic molecules that are useful in medicine, agriculture and potentially other areas such as flavouring, fragrances and materials

Planar Chiral [2.2]Paracyclophane-Based Bisoxazoline Ligands and Their Applications in Cu-Mediated N–H Insertion Reaction

New catalysts for important C–N bond formation are highly sought after. In this work, we demonstrate the synthesis and viability of a new class of planar chiral [2.2]paracyclophane-based bisoxazoline (BOX) ligands for the copper-catalyzed N–H insertion of α-diazocarbonyls into anilines. The reaction features a wide substrate scope and moderate to excellent yields, and delivers the valuable products at ambient conditions

Copper-Catalyzed Oxidation of Alkenes and Heterocycles

A variety of copper species catalyze the allylic oxidation of olefins and the introduction of an ester group at the α-position of a heterocycle. Both transformations are closely related in terms of reaction conditions and radical species involved. This short review highlights the progress made in these two types of oxidations, emphasizing work that has occurred within the last fifteen years

Photocatalytic enantioselective α-aminoalkylation of acyclic imine derivatives by a chiral copper catalyst

廉价金属催化的可见光反应为惰性化学键的断裂和重组提供了新的策略，且具有经济、低毒、易操作的特点，是发展绿色合成方法的理想选择。然而，由于这些金属配合物的可见光吸收相对弱、光化学稳定性较差、激发态寿命短等缺点，相关研究较为有限，特别是其催化的可见光不对称合成因涉及自由基等高活性物种转化的立体化学控制，是极具挑战性却有着重大意义的研究方向。课题组在近期工作基础上以易得、易修饰的手性噁唑啉-铜（II）配合物作为催化剂，在可见光照射下实现了非环亚胺的高对映选择性α-胺基烷基化反应，为手性二胺及其衍生物的制备提供了一条经济、便捷的路线。控制实验充分证明了其机理。该项研究利用单一催化剂发挥多重功效，使转化困难的反应在极为简单、温和的条件得以实现，为多功能催化及绿色合成方法的发展提供了新的思路。 该研究由龚磊副教授指导，实验部分由已毕业硕士生韩博闻（第一作者）、博士生李延军、硕士生余莹合作完成。 此文章并被选为Editors’ Highlights论文。Copper-based asymmetric photocatalysis has great potential in the development of green synthetic approaches to chiral molecules. However, there are several formidable challenges associated with such a conception. These include the relatively weak visible light absorption, short excited-state lifetimes, incompatibility of different catalytic cycles, and the difficulty of the stereocontrol. We report here an effective strategy by means of single-electron-transfer (SET) initiated formation of radicals and photoactive intermediates to address the long-standing problems. Through elaborate selection of well-matched reaction partners, the chiral bisoxazoline copper catalyst is engaged in the SET process, photoredox catalysis, Lewis acid activation and asymmetric induction. Accordingly, a highly enantioselective photocatalytic α-aminoalkylation of acyclic imine derivatives has been accessed. This strategy sheds light on how to make use of diverse functions of a single transition metal catalyst in one reaction, and offers an economic and simplified approach to construction of highly valuable chiral vicinal diamines.We gratefully acknowledge funding from the National Natural Science Foundation of China (grant no. 21572184), the Natural Science Foundation of Fujian Province of China (grant no. 2017J06006), and the Fundamental Research Funds for the Central Universities (grant no. 20720190048).研究工作得到国家自然科学基金（21572184）、福建省杰出青年基金（2017J06006）、厦门大学校长基金（20720190048）、南强青年拔尖人才计划（B类）等的支持