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511.
Wei Sun Dr. Meng-Yang Hu Zhan-Sheng Lu Dr. Ming-Yao Huang Xin-Yu Zhang Prof. Dr. Shou-Fei Zhu 《Angewandte Chemie (International ed. in English)》2023,62(51):e202315473
Stereoconvergent transformation of E/Z mixtures of olefins to products with a single steric configuration is of great practical importance but hard to achieve. Herein, we report an iron-catalyzed stereoconvergent 1,4-hydrosilylation reactions of E/Z mixtures of readily available conjugated dienes for the synthesis of Z-allylsilanes with high regioselectivity and exclusive stereoselectivity. Mechanistic studies suggest that the reactions most likely proceed through a two-electron redox mechanism. The stereoselectivity of the reactions is ultimately determined by the crowded reaction cavity of the α-diimine ligand-modified iron catalyst, which forces the conjugated diene to coordinate with the iron center in a cis conformation, which in turn results in generation of an anti-π-allyl iron intermediate. The mechanism of this stereoconvergent transformation differs from previously reported mechanisms of other related reactions involving radicals or metal-hydride species. 相似文献
512.
Xuan Wen Wenbin Xie Yawen Li Xiaoying Ma Zhaoying Liu Xiao Han Kaikai Wen Prof. Fengjiao Zhang Prof. Yuze Lin Prof. Qinqin Shi Prof. Aidong Peng Prof. Hui Huang 《Angewandte Chemie (International ed. in English)》2023,62(40):e202309922
The Suzuki–Miyaura cross-coupling is one of the most important and powerful methods for constructing C−C bonds. However, the protodeboronation of arylboronic acids hinder the development of Suzuki–Miyaura coupling in the precise synthesis of conjugated polymers (CPs). Here, an anhydrous room temperature Suzuki–Miyaura cross-coupling reaction between (hetero)aryl boronic esters and aryl sulfides was explored, of which universality was exemplified by thirty small molecules and twelve CPs. Meanwhile, the mechanistic studies involving with capturing four coordinated borate intermediate revealed the direct transmetalation of boronic esters in the absence of H2O suppressing the protodeboronation. Additionally, the room temperature reaction significantly reduced the homocoupling defects and enhanced the optoelectronic properties of the CPs. In all, this work provides a green protocol to synthesize alternating CPs. 相似文献