1,3-Dipolar cycloaddition of nitrones with nitriles.
作者:Pedro H.H. Hermkens、Jan H.v. Maarseveen、Chris G. Kruse、Hans W. Scheeren
DOI:10.1016/s0040-4020(01)89838-0
日期:——
nitriles 14–16, proceeded under thermal as well as under high pressure conditions with complete regioselectivity to give Δ4-1,2,4-oxadiazolines 17–19. In general, the cycloaddition seemed to be controlled by a HOMO(nitrone)- LUMO(nitrile) interaction. However, a crossover in the orbital control is probable observed with nitrile 16c. Nitrone-nitrile cycloadditions are normal type II cycloadditions so that
硝酮的1,3-偶极环加成1-6与腈14-16,下热以及与完整区域选择性高的压力条件下进行,得到Δ 4 -1,2,4-恶二唑啉17-19。通常,环加成似乎受HOMO(硝酮)-LUMO(腈)相互作用控制。但是,用腈16c可能会在轨道控制中发生交叉现象。腈-腈环加成是正常的II型环加成,因此腈具有U形反应性曲线。溶剂极性和Hammett方程的动力学研究表明,从机理上讲,腈-腈环加成与硝基-烯烃环加成是一致的。