Facile, Regioselective [4 + 2] Cycloaddition Involving 1-Aryl-4-phenyl-1-azadienes and Allenic Esters: An Efficient Route to Novel Substituted 1-Aryl-4-phenyl-1,4-dihydropyridines
作者:M. P. S. Ishar、Kamal Kumar、Sumanjit Kaur、Shiv Kumar、Navdeep K. Girdhar、Satish Sachar、Alka Marwaha、Ashish Kapoor
DOI:10.1021/ol010026a
日期:2001.7.1
undergo facile, regioselective [4 + 2] cycloaddition to the C2,C3 pi-bond of allenic esters in refluxing benzene, and the formed adducts undergo a 1,3-H shift to afford novel 2-alkyl-1-aryl-3-ethoxycarbonyl-4-phenyl-1,4-dihydropyridines (78-97%). However, when the reaction is carried at room temperature, besides the [4 + 2] addition, the [2 + 2] mode of addition involving C=N of azadiene and C3,C4 pi-bond
[反应:请参阅文本] 1-芳基-4-苯基-1-氮杂二烯在回流的苯中的烯丙酯的C2,C3π键上进行容易的区域选择性[4 + 2]环加成,生成的加合物经历1, 3-H转变得到新颖的2-烷基-1-芳基-3-乙氧基羰基-4-苯基-1,4-二氢吡啶(78-97%)。然而,当反应在室温下进行时,除了[4 + 2]加成以外,还涉及[2 + 2]的加成方式,涉及氮杂二烯的C = N和烯丙酸酯的C 3,C 4π键。所得的N-芳基-2-乙氧基-羰基-亚甲基-4-苯乙烯基氮杂环丁烷(17-28%)在硅胶上进行重组,得到2-环己烯-1-酮。