Cyclization of alk-4-ynals with o-diaminoarenes as a selective one-pot synthesis of arylmethylidene-substituted 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazoles and 7,8-dihydro-6H-pyrrolo[1’,2’:1,2]imidazo[4,5-b]pyridines
作者:V. D. Gvozdev、K. N. Shavrin、E. G. Baskir、M. P. Egorov、O. M. Nefedov
DOI:10.1007/s11172-016-1517-6
日期:2016.7
3-diaminopyridine gave 7,8-dihydro-6H-pyrrolo[1’,2’:1,2]imidazo[4,5-b]pyridines in up to 56% yields. The distinguishing feature of the processes under study is proceeding of their key step that is intramolecular hydroamination of the triple bond, as a 5-exo-dig-cyclization. The necessity for the application of drastic conditions required for these processes is in agreement with the results of quantum chemical
芳基亚甲基取代的 2,3-二氢-1H-吡咯并[1,2-a]苯并咪唑的一锅合成基于 alk-4-ynals 与 1,2-二氨基苯在 DMSO 中在连续催化下与 NH4Br 和基地被建议。在这些过程中使用 KOH 作为碱导致最终产品的 E-异构体的选择性形成,产率为 48-66%,而碱性较低的 K2CO3 以 32-82% 的产率产生相应的 Z-异构体。涉及 2,3-二氨基吡啶的类似环化反应以高达 56% 的产率得到 7,8-二氢-6H-吡咯并[1',2':1,2]咪唑并[4,5-b]吡啶。正在研究的过程的显着特征是进行其关键步骤,即三键的分子内加氢胺化,作为 5-exo-dig-环化。