Intramolecular nucleophilic addition to unsaturated carbon. Dependence of cyclization efficiency on the method of carbon-carbon bond cleavage utilized to generate the reactive species
The rhodium-catalyzed methylenation of aldehydes using trimethylsilyldiazomethane and triphenylphosphine produces a variety of terminal alkenes in excellent yields. These mild and nonbasic reaction conditions allow the conversion of enolizable substrates (keto aldehydes and nonracemic alpha-substituted aldehydes) to terminal alkenes without epimerization. Optimization of the reaction conditions led
Reductive Alkylation of Alkenyl Acetates with Alkyl Bromides by Nickel Catalysis
作者:Rong‐De He、Yunfei Bai、Guan‐Yu Han、Zhen‐Zhen Zhao、Xiaobo Pang、Xiaobo Pan、Xue‐Yuan Liu、Xing‐Zhong Shu
DOI:10.1002/anie.202114556
日期:2022.1.21
A new C−C bond-forming reaction between alkenyl acetates and alkyl bromides was achieved by reductive nickel catalysis. This method offers very mild reaction conditions for facile and precise synthesis of structurally versatile aliphatic alkenes using readily available and stable alkenyl reagents. It allows for a gram-scale reaction and modification of biologically active molecules, and it affords
Rhodium‐Catalyzed Divergent Arylation of Alkenylsulfonium Salts with Arylboroxines
作者:Yun Ye、Jie Zhu、Haijiao Xie、Yinhua Huang
DOI:10.1002/anie.202212522
日期:2022.12.5
A ligand-controlled rhodium-catalyzed divergent arylation of alkenyl thianthrenium salts with arylboroxines which allows switchable synthesis of both terminal and internal alkene products in a highly selective manner is reported. The use of a diene ligand guides the reaction toward cine-arylation affording terminal alkenes, while the use of a phosphine ligand switches the reaction to ipso-arylation
A variety of terminal alkenes are produced in excellent yields by the rhodium(I)-catalyzed methylenation of aldehydes using TMSCHN2 and PPh3 [Eq. (1)]. These mild reaction conditions allowed the conversion of enolizable substrates and the chemoselective methylenation of aldehydes over ketones. TMS=trimethylsilyl.