Experimental and Theoretical Investigation of Hydrogenative Cyclization of Allenynes
作者:Hyo-Tong Kim、Hyo-Sang Yoon、Woo-Young Jang、Youn K. Kang、Hye-Young Jang
DOI:10.1002/ejoc.201100280
日期:2011.7
Upon platinum-catalyzed hydrogenation, allenynes underwent reductive cyclization to provide hetero- and carbocycles with completely controlled regio- and stereoselectivity. By employing hydrogen as a reductant, the use of stoi
在铂催化的氢化作用下,丙炔进行还原环化以提供具有完全受控的区域和立体选择性的杂环和碳环。通过使用氢气作为还原剂,使用 stoi
Synthesis of 3-Acyl-4-alkenylpyrrolidines by Platinum-Catalyzed Hydrative Cyclization of Allenynes
A series of nitrogen-tethered allenynes (‘5-aza-1,2-dien-7-ynes’) 1 were transformed to the corresponding 3-acyl-4-alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl2 in MeOH at 70°. Initial Pt-promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2, the intermediate is intercepted
Allenynes underwent cycloisomerization in the presence of a catalytic amount of platinum(II) chloride at 80 °C to give bicyclic cyclobutenes. A mechanism involving non-classical carbocationic intermediates was proposed for the formation of cyclobutenes.
TfOH- and HBF<sub>4</sub>-Mediated Formal Cycloisomerizations and [4+3] Cycloadditions of Allene-alkynylbenzenes
作者:Yu Xiang、Zining Li、Lu-Ning Wang、Zhi-Xiang Yu
DOI:10.1021/acs.joc.8b00393
日期:2018.8.3
prepared allene-alkynylbenzenes to give pyrrolidines and cyclopentanes derivatives was developed. This reaction is initiated by the generation of allylic cation from allene, followed by alkyne’s reaction with the allylic cation, to give a vinylcation, which is finally intercepted by the triflate (TfO) anion. This cycloisomerization can be further tuned to become an acid-mediated intramolecular formal
Wilkinson’s catalyst [RhCl(PPh3)3] catalyzed a cycloisomerization of allenynes which possess geminal methyls on the allene terminus and an intramolecular ene-type reaction proceeded to give various cross-conjugated trienes. Thermal Diels-Alder reaction of the obtained triene was examined to give a bicyclic compound in a high yield.