作者:Hongwei Wang、Rapolu Kiran Kumar、Yang Yu、Lin Zhang、Zhaohong Liu、Peiqiu Liao、Xihe Bi
DOI:10.1002/asia.201601024
日期:2016.10.20
molecules. The isocyanide–isocyanide [3+2] cross‐cycloadditionreaction constitutes a straightforward method to access imidazoles starting from the easily available chemicals. So far, only three successive reports are known and all lead to the formation of 1,4‐disubstituted imidazoles. Here, we report the first isocyanide–isocyanide [3+2] cross‐cycloadditionreaction allowing for the formation of 1,4,5‐trisubstituted
unprecedented heteroannulation process created four chemical bonds in a single operation with the isocyano group acting formally as a polarized double bond and phenyl vinyl selenone as a latent 1,3‐dipole. The phenylselenonyl group played a triple role as an electron‐withdrawing group to activate the 1,4‐addition, a leaving group, and a latent oxidant in this transformation.
在催化量的Cs 2 CO 3存在下,烷基异氰化物,苯基乙烯基硒酮和水的反应得到了恶唑烷-2-酮,收率很高。这种空前的异环化过程在一次操作中产生了四个化学键,异氰基在形式上起极化双键作用,苯基乙烯基硒酮起潜在的1,3-偶极作用。苯基硒壬基在该转化过程中作为吸电子基团发挥了三重作用,以激活1,4加成,一个离去基团和一个潜在的氧化剂。
Tertiary Amines as Synthetic Equivalents of Vinyl Cations: Zinc Bromide Promoted Coupling of Propargylamines with α-Isocyanoacetamides To Give 2,4,5-Trisubstituted Oxazoles Initiated by an Internal Redox Process
作者:Yann Odabachian、Qian Wang、Jieping Zhu
DOI:10.1002/chem.201302106
日期:2013.9.9
Crabée interrupted: Propargylamines 1 react with α-isocyanoacetamides 2 in the presence of zinc bromide to afford vinyl oxazoles 3. The transformation, wherein the propargylamine acts as a vinyl cation syntheticequivalent, involves a domino sequence incorporating a 1,5-hydride shift, intermolecular trapping/cyclization, and a 1,6-elimination (see scheme).
1,6-Addition Arylation of para-Quinone Methides: An Approach to Unsymmetrical Triarylmethanes
作者:Shang Gao、Xiuyan Xu、Zhenbo Yuan、Haipin Zhou、Hequan Yao、Aijun Lin
DOI:10.1002/ejoc.201600385
日期:2016.6
A 1,6-addition arylation reaction of para-quinone methides with α-isocyanoacetamides and electron-rich aromatic compounds under metal-free conditions has been developed. BF3·Et2O plays two roles in the reaction: catalyzing the cyclization of α-isocyanoacetamides to give oxazoles, and activating the para-quinone methides to achieve the 1,6-addition arylation process. The reaction shows good functional
intramolecular cyclization to 5-aminooxazoles. Despite the formation of the aryl anion as a key intermediate, the reaction displays a stereoconservative course, allowing for the preparation of enantiomerically pure α-benzoylamino amides. Finally, the syntheticutility of the reported MCR was exemplified by the preparation of proglumide, a cholecystokinin antagonist.