Stereoselective Csp3–Csp2 Bond‐Forming Reactions by Transition‐Metal‐Free Reductive Coupling of Cyclic Tosylhydrazones with Boronic Acids

The reactions between alkenylboronic acids and tosylhydrazones derived from substituted cyclohexanones lead to the construction of disubstituted cyclohexanes with total regio‐ and stereoselectivity. In these transition‐metal‐free processes, a Csp³?Csp² and Csp³?H bond are formed on the same carbon atom. The stereoselective reaction is general for 2‐, 3‐, and 4‐substituted cyclohexanone tosylhydrazones, as well as for 2‐substituted cyclopentanones. However, no stereoselectivity is observed for acyclic derivatives. DFT computational modeling suggests that the stereoselectivity of the reaction is determined by the approach of the boronic acid to the diazocyclohexane on its most stable chair conformation through an equatorial trajectory.     

Synthesis of α-arylalkylferrocenes through cesium fluoride-promoted coupling of arylboronic acids with N-tosylhydrazones

A cesium fluoride-promoted reductive coupling reaction of acylferrocene tosylhydrazones with arylboronic acids has been developed, producing highly substituted α-arylalkylferrocenes in moderate to excellent yields. The reaction employs anionic fluorine to facilitate the cleavage of C–B bond. The developed methodology demonstrates a wide substrate scope and high functional groups tolerance. Moreover, the α-arylalkylferrocenes compounds were also obtained on a multi-gram scale.     

Copper‐catalyzed C‐N coupling reaction of tosylhydrazones

Tosylhydrazones are a kind of labile and highly reactive compounds, which are apt to be transformed into reactive diazo compounds and then into extremely reactive carbenes under the basic condition. In order to fulfil the valuable C‐N coupling reaction, diaryliodonium salts are evaluated and prove to be a class of efficient electrophiles. The reaction with ligand‐free copper salt as catalyst shows a wide range of substrate scope. A plausible mechanism is proposed.     

钯催化选择性构筑(Z)-[3]戟烯反应研究

本工作发展了钯催化下芳甲醛对甲苯磺酰腙与膦酰基取代联烯的偶联反应, 顺利地以中等至良好的收率及较高的立体选择性制备了一系列(Z)-[3]戟烯衍生物. 不同于烷基取代的苯磺酰腙与烯烃的简单偶联, 该反应使用芳甲醛对甲苯磺酰腙作为底物, 经由1,3-钯迁移历程成功构筑了两个C=C双键. 在最优反应条件下, 该反应展示了较宽的底物适用范围和较高的立体选择性. 最终以31个反应实例获得一系列(Z)-[3]戟烯衍生物, 最高79%分离产率和>20:1 Z/E选择性, 为(Z)-[3]戟烯衍生物的合成应用提供了简便高效的方法.     

White Light/NIS-Promoted Aminoselenylation of Alkenes by Using N-Tosylhydrazones

A white light/iodosuccinimide (NIS)-promoted three component reaction of alkenes, N-sulfonylhydrazones, and diorganyl diselenides for synthesis of organylselenylethyl sulfonylhydrazones under air is disclosed. This intermolecular aminoselenylation of alkenes using N-tosylhydrazones as nitrogen source was performed under mild conditions and well tolerated for common groups. In addition, heteroaryl and aliphatic diselenides also gave the target compounds. Gram-scale reaction also carried out smoothly. This protocol has a wide range of substrates and affords moderate to high yields and excellent regioselectivities. The photoactive intermediates from the interaction between NIS and diphenyl diselenide was detected by UV-visible absorption spectra, which matches the wavelength of the applied white LED. A reasonable mechanism was proposed based on UV-visible light experiments and control experiments.     

Base‐Promoted Coupling of Carbon Dioxide,Amines, and N‐Tosylhydrazones: A Novel and Versatile Approach to Carbamates

A base‐promoted three‐component coupling of carbon dioxide, amines, and N‐tosylhydrazones has been developed. The reaction is suggested to proceed via a carbocation intermediate and constitutes an efficient and versatile approach for the synthesis of a wide range of organic carbamates. The advantages of this method include the use of readily available substrates, excellent functional group tolerance, wide substrate scope, and a facile work‐up procedure.     

A Novel Metal‐free Reductive Esterification of N‐Tosylhydrazones with Carboxylic Acids

A novel method for the synthesis of esters via reductive coupling of N‐tosylhydrazones with carboxylic acids under metal‐free conditions has been developed. Various functional groups were found to be tolerable under the reaction conditions to afford low to good yields.