3-Nitrocoumarin Amidines: A New Synthetic Strategy for Substituted [1]Benzopyrano[3,4-d]imidazol-4(3H)-ones
作者:Egle M. Beccalli、Alessandro Contini、Pasqualina Trimarco
DOI:10.1002/ejoc.200300109
日期:2003.10
A new synthesis of substituted [1]benzopyrano[3,4-d]imidazol-4(3H)-ones, starting from 3-nitrocoumarin N-functionalized amidines 3, has been developed. When the 3-nitro-amidines 3 were treated with NaBH4 in the presence of 10% palladium on charcoal, 2-substituted [1]benzopyrano[3,4-d]imidazol-4(3H)-ones 4 were produced. Structure elucidation of compounds 4 revealed that they exist as one of the three
一种新的取代 [1] 苯并吡喃并 [3,4-d] 咪唑-4(3H)-酮的合成方法,从 3-硝基香豆素 N-功能化脒 3 开始,已被开发出来。当在 10% 钯炭存在下用 NaBH4 处理 3-硝基脒 3 时,产生了 2-取代的 [1] 苯并吡喃并 [3,4-d] 咪唑-4(3H)-酮 4。化合物 4 的结构解析表明它们作为三种可能的互变异构结构之一(即 4dα)存在。4d 烷基化得到 6,以及对 6 的 NOE 实验和能量计算允许鉴定 4 种衍生物的最有利结构。或者,通过亚磷酸三乙酯还原 3-硝基脒 3,通过氮烯中间体、环化和 [1.5] σ 移位,产生 2-吗啉代-3-烷基-[1] 苯并吡喃 [3,4-d]咪唑-4(3H)-酮 7.