Bridgehead nitrogen heterocycles which contain the quinazoline moiety – synthesis and cycloaddition of 1,2-dihydroquinazoline 3-oxides
作者:Frances Heaney、Tomas McCarthy、Mary Mahon、V. McKee
DOI:10.1039/b511998g
日期:——
first ever examples of 1,3-dipolar trapping of these nitrones to homonuclear dipolarophiles is described. The new dipoles 8 reacted with N-methyl maleimide, generating diastereomeric adducts 14-16. In the reaction between 8 and dimethyl acetylenedicarboxylate, primary cycloadducts 17 and/or stable rearrangement products, azomethine ylides 18, are formed depending on the substitution pattern of the dipole
描述了1,2-二取代的1,2-二氢喹唑啉3-氧化物8的新颖合成以及这些硝酮与同核双亲性物的1,3-偶极捕集的第一个实例。新的偶极子8与N-甲基马来酰亚胺反应,生成非对映体加合物14-16。在8与乙炔二甲酸二甲酯之间的反应中,取决于偶极的取代方式,形成伯环加合物17和/或稳定的重排产物偶氮甲亚胺基化物18。X射线晶体学分析明确地确定了18c的结构。还提出了通过将[3 + 2]加成8a到21,即乙炔基二羧酸二甲酯四聚体而形成的环丙基异唑并喹唑啉22的X射线晶体结构测定。