The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of
Spontaneous formation of PMB esters using 4-methoxybenzyl-2,2,2-trichloroacetimidate
作者:Jigisha P. Shah、Christopher M. Russo、Kyle T. Howard、John D. Chisholm
DOI:10.1016/j.tetlet.2014.01.097
日期:2014.3
Carboxylic acids are converted to the corresponding 4-methoxybenzyl (PMB) esters with 4-methoxybenzyl-2,2,2-trichloroacetimidate in the absence of an acid catalyst. This operationally simple procedure is a highly effective method for the formation of PMB esters. The reaction is promoted by the carboxylic acids themselves in excellent yields (72–99%). Sterically hindered carboxylic acids, which provide
Effective Synthesis of Benzyl 3-Phenylpropiolates Via Copper(I)-Catalyzed Esterification of Alkynoic Acids with Benzyl Halides Under Ligand-Free Conditions
corresponding benzyl halides and alkynoic acids under ligand-free condition. This methodology is also suitable for aromatic and α,β-unsaturated acids. The desired esters could be obtained in good yields.Graphical AbstractWe developed an efficient way to prepare benzyl 3-phenylpropiolates via copper-catalyzed coupling between corresponding benzyl halides and alkynoic acids under ligand-free condition
Unprecedented Multicomponent Organocatalytic Synthesis of Propargylic Esters via CO<sub>2</sub>Activation
作者:Argyro T. Papastavrou、Martin Pauze、Enrique Gómez‐Bengoa、Georgios C. Vougioukalakis
DOI:10.1002/cctc.201900207
日期:2019.11.7
providing the corresponding propargylic esters in low to excellent yields. DFT calculations on the mechanism of this transformation indicate that the reaction is initiated with the formation of an NHC‐carboxylate, by addition of the carbene to a molecule of CO2. Then, the nucleophilic addition of this species to the corresponding chlorides has been computed to be the rate limiting step of the process
The carboxylative coupling of aryl/alkyl terminalalkynes, CO2 and benzyl halides was investigated using silver iodide as the catalyst and Cs2CO3 as the base in CH3CN under ligand-free conditions. This reaction protocol shows a wide substrate scope and high functional group tolerance ability for benzyl halides, in which various functionalized benzyl 2-alkynoates were achieved in good yields. This one-pot
芳基/烷基末端炔烃,CO的carboxylative耦合2使用碘化银作为催化剂和Cs和苄基卤化物进行了研究2 CO 3在CH基座3无配体的条件下,CN。该反应方案显示出宽的底物范围和对苄基卤的高官能团耐受能力,其中以良好的产率获得了各种官能化的2-炔基苄基酯。这种一锅,无配体和CH 3 CN介导的反应被证明易于处理,并且在大气CO 2压力下可以促进。