First example of Diels–Alder reaction in the 2,3,4,4a-tetrahydroquinoline series. Synthesis of hydrogenated 5,8-ethanoquinolines
作者:Eugeniya V. Nikitina、Victor N. Khrustalev、Dmitry G. Grudinin、Flavien A.A. Toze、Vladimir V. Kouznetsov、Fedor I. Zubkov
DOI:10.1016/j.tet.2010.02.020
日期:2010.4
Diels–Alder reactions in the 2,3,4,4a-tetrahydroquinolines series were studied for the first time. It was shown that these dienes demonstrate only moderate reactivity. [4+2] Cycloaddition occurs stereo- and regioselectively only for alkenes bearing an electron-withdrawing group (acrylonitrile, maleic anhydride, dimethyl acetylene dicarboxylate, methyl propiolate). In this case, endo-Diels–Alder adducts, spiroannelated
首次研究了2,3,4,4a-四氢喹啉系列中的Diels-Alder反应。结果表明,这些二烯仅表现出中等反应性。[4 + 2]环加成反应仅对带有吸电子基团的烯烃(丙烯腈,马来酸酐,乙炔二羧酸二甲酯,丙炔酸甲酯)具有立体选择性和区域选择性。在这种情况下,高产率形成了内-Diels-Alder加合物,即螺旋退火的5,8-乙基喹啉。作为高反应性二烯组分的环戊二烯与2,3,4,4a-四氢喹啉作为亲二烯体反应。富含电子的不饱和化合物(N-乙烯基吡咯烷酮,乙烯基乙基醚,苯乙炔)对该环加成反应呈惰性。