14604-46-7Relevant articles and documents
Vinylcyclobutanols: A composite functional group?
Trost, Barry M.,Chen, Deborah W. C.
, p. 12541 - 12554 (1996)
The effect of small strained rings on chemical reactivity was probed by the examination of the behavior of vinylcyclobutanols as terminators in cyclization reactions. The substrates were readily available by the addition of vinyllithium reagents bearing acetals as cyclization initiators to cyclobutanone. Bronsted and Lewis acids both promoted cyclization in contrast to vinylcyclopropanol terminators for which Bronsted acids failed. The products are spirocycles consisting of a cyclopentanone derived from ring expansion of the cyclobutanol and the second ring derived by attack of the terminator on the initiator. Spirocyclization to [4.5] and [4.6] systems proceeded smoothly, whereas spirocyclization to a [4.7] system failed. Attaching the cyclization termini to a preexisting ring system (whereby tricycles consisting of a fused bicycle and a spirocycle are formed) expands the scope of the cyclization to include the [4.7] ring system even at 0.01 M, a rather high concentration for such an unfavorable ring system. The diastereoselectivity generally placed the initiator substituent and the carbon-carbonyl bond of the cyclopentanone ring trans on the newly formed ring. Cyclic acetals and the free aldehyde also served as initiators. The mechanistic implications of these observations are discussed.
Copper-Catalyzed Perfluoroalkylation of Alkynyl Bromides and Terminal Alkynes
Fan, Shilu,Zheng, Chenggong,Zheng, Kaiting,Li, Junlan,Liu, Yaomei,Yan, Fangpei,Xiao, Hua,Feng, Yi-Si,Zhu, Yuan-Yuan
supporting information, p. 3190 - 3194 (2021/05/05)
A copper-catalyzed one-pot perfluoroalkylation of alkynyl bromides and terminal alkynes has been disclosed, and the corresponding perfluoroalkylated alkynes could be attained in good to excellent yields. The new straightforward transformation shows high efficiency (0.01-0.5 mol % catalyst loading), broad substrate scope, and remarkable functional group tolerance and provides a facile approach for useful application in life and material sciences.
Copper-Catalyzed Oxidative Fragmentation of Alkynes with NFSI Provides Aryl Ketones
Chen, Hanfei,Cheng, Hao,Huang, Yifan,Jin, Chaochao,Song, Weihan,Tan, Chen,Tan, Jiajing,Tang, Lin,Yang, Fang,Zhang, Shuaifei
supporting information, (2020/11/03)
A copper-catalyzed oxidative cleavage reaction of alkynes using NFSI and TBHP was described. Various terminal and internal alkyne substrates were employed to render quick access to aryl ketone products in moderate to good yields. NFSI not only functioned as N-centered radical precursors but also engaged in the aryl group migration. Mechanistic studies also suggested the important role of water in the title reactions.
Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
, p. 8083 - 8092 (2019/08/26)
A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
