Pyrimidine annelated heterocycles - synthesis and cycloaddition of the first pyrimido[1,4]diazepine N-oxides
作者:Frances Heaney、Cathriona Burke、Desmond Cunningham、Patrick McArdle
DOI:10.1039/b007163n
日期:——
5-Formyl- and 5-acetyl-4-(alkenylamino)pyrimidines 5 have been prepared as precursors to novel pyrimido[1,4]diazepine N-oxides 3. In addition to cyclisation to the targeted dipoles the substrates 5 have also been observed to form imidazopyrimidines 12 and 39via an intramolecular Michael addition; additionally 5b has been observed to form the pyrimidoazepinone 42. Aldonitrone 3a cycloadded readily to olefinic dipolarophiles; ketodipole 3b did not share this reactivity. Both dipoles reacted with acetylenic dipolarophiles but the ensuing cycloadducts 37 were unstable; facile ring contraction of their isoxazolopyrimidodiazepine skeletons to the pteridine nucleus is noted. The structure of 37c has been determined by X-ray crystallography.
我们制备了 5-甲酰基和 5-乙酰基-4-(烯基氨基)嘧啶 5,作为新型嘧啶并[1,4]二氮杂卓 N-氧化物 3 的前体。除了环化成目标偶极外,还观察到底物 5 通过分子内迈克尔加成形成咪唑嘧啶 12 和 39;此外,还观察到 5b 形成嘧啶氮杂卓酮 42。氨甲环酮 3a 很容易与烯烃类双极性化合物发生环加成反应;而酮二极 3b 则没有这种反应性。这两个偶极都与乙炔双亲极性物质发生了反应,但随之产生的环载产物 37 不稳定;它们的异噁唑并嘧啶二氮杂卓骨架与蝶啶核的环收缩很容易。37c 的结构已通过 X 射线晶体学确定。