Reactivity of four-membered cyclic nitrones in 1,3-cycloaddition reactions. X-Ray crystal structure of 7-(2,6-dichlorophenyl)-N,N-diethyloctahydro-6-methyl-1,3-dioxo-2-phenylazeto[1,2-b]pyrrolo[3,4-d]isoxazole-6-carboxamide
作者:Peter J. S. S. van Eijk、Willem Verboom、Frank C. J. M. van Veggel、David N. Reinhoudt、Sybolt Harkema
DOI:10.1002/recl.19881070308
日期:——
diethyl maleate yielded the corresponding azeto[1,2-b]pyrrolo[3,4-d]isoxazole derivatives, 8 and 9, respectively. The exclusive formation of the exo-conformation of the cycloadducts was unequivocally proven by X-ray analysis of 8a. Reaction of 2a with methyl 2-propenoate (methyl acrylate) and 3-buten-2-one (methyl vinyl ketone) gave regio- and stereoselectively the corresponding exo-5′-isoxazolidine
四元环硝酮1和2与乙炔二羧酸二甲酯反应,生成相应的环加合物3,4。2a与苯乙炔反应后,获得5'-取代的异恶唑啉衍生物5。2a与丙酸甲酯的反应分别生成4'-和5'-环加合物δ,7和6的1:4混合物。的反应2a-c中与N-苯基马来酰亚胺和的图2a与马来酸二乙酯,得到相应azeto [1,2-b]吡咯并[3,4-d]异恶唑衍生物,8和9, 分别。Xa射线分析8a明确证明了环加合物的exo-构象的排他性形成。的反应图2a用甲基-2-丙烯酸酯(甲基丙烯酸酯)和3-丁烯-2-酮(甲基乙烯基酮),得到区域选择性和立体选择性地对应的外-5'-异恶唑烷cycloadducts,10和11,分别。环加合物的立体化学由1 H NMR数据推导。炔烃和烯烃双极性亲和剂均从空间较少受阻的一侧接近四元环硝酮,导致所获得的环加合物的(区域和)立体选择性形成。