Magnesium Ion Assisted Highly Regio- and Chemoselective Reduction of 5<i>H</i>-Pyrrolo[3,4-<i>b</i>]pyridine-5,7(6<i>H</i>)-diones with Sodium Borohydride. A Convenient Synthesis of 6,7-Dihydro-7-hydroxy-5<i>H</i>-pyrrolo[3,4-<i>b</i>]pyridin-5-ones
作者:Takehiko Goto、Michio Konno、Minoru Saito、Ryu Sato
DOI:10.1246/bcsj.62.1205
日期:1989.4.15
were predominantly obtained in excellent yield by the reduction of the corresponding 5,7-diones with sodium borohydride in the presence of Mg ion at 0 °C. The highly regioselective production of the 7-hydroxy lactam in preference to the 5-hydroxy isomer was reasonably interpreted in terms of a chelate complex formation between the dione and Mg ion. The regioisomeric assignment was achieved by the transformation
通过用硼氢化钠还原相应的 5,7-二酮,6-取代和未取代的 6,7-二氢-7-羟基-5H-吡咯并[3,4-b]吡啶-5-酮主要以优异的收率获得在 0 °C 存在 Mg 离子的情况下。7-羟基内酰胺优先于 5-羟基异构体的高度区域选择性生产被合理地解释为二酮和镁离子之间的螯合物形成。通过将 7-羟基内酰胺转化为 2-(羟甲基)-3-吡啶甲酰胺,可将其转化为已知的氮杂苯酞、呋喃 [3,4-b] 吡啶-5(7H)-酮,从而实现区域异构分配。此外,发现在低于 0 °C 时仍保持高化学选择性,只得到部分还原产物羟基内酰胺。
New Synthesis of Pyrido[2,3-<i>d</i>] and [3,2-<i>d</i>]Oxazines
作者:Amin F. Fahmy、Jürgen Sauer、Mohamed Salah K.Youssef、Mohamed Said AbdelHalim、Mamdouh A. Hassan
DOI:10.1080/00397919808004864
日期:1998.8
Abstract N-Hydroxyquinolinimide 1 reacts with each of aromatic amines, hydrazine hydrate and aromatic hydrocarbons to give arylcarbamoyl pyridines 2, pyrrolopyridines 3, pyridopyridazines 4 and pyridooxazinones 5 and 6. The heterocycles 5 and 6 can be transformed to the condensed systems, triazolopyridopyridazines 14 and 15 through series of reactions.