呋喃已被用作合成一系列杂环化合物的支架,第一步是探索其对亚硝基和偶氮烯烃的亲二烯键行为。这些环加合物,4a,7a-二氢-4 H-呋喃[2,3- e ] [1,2]恶嗪和1,4,4a,7a-四氢呋喃[3,2- c ]的酸催化重排对哒嗪进行了研究。使用1当量 在TFA中,衍生自呋喃和2-甲基呋喃的双环杂环通过六元环的开环伴随呋喃环的芳构化而转化为带有掺入肟和基的侧链的呋喃。使用TFA作为溶剂导致经由螺环中间体的重排,随后呋喃开环以提供官能化的异恶唑或吡唑。此外,在催化量的p存在下,通过热分解的呋喃开环反应,将呋喃芳构化被排除的2,5-二甲基呋喃衍生的呋喃恶嗪有效地转化为6 H -1,2-恶嗪。-甲苯磺酸。四氢呋喃[3,2- c衍生自呋喃和二甲基呋喃的]哒嗪经过酸催化的加成反应,当在醇或水存在下,生成6-取代的六氢呋喃[3,2- c ]哒嗪。
Addition of malonic esters to azoalkenes generated in situ from α-bromo- and α-chlorohydrazones
作者:Aleksandr O. Kokuev、Sema L. Ioffe、Alexey Yu. Sukhorukov
DOI:10.1016/j.tetlet.2021.153414
日期:2021.10
Michael addition of malonicesters to azoalkenes generated in situ from α-bromo- and α-chlorohydrazones was accomplished. Both aliphatic and aromatic substrates bearing different functional groups are tolerated. The use of a strong base (sodium hydride) for generation of azoalkenes and deprotonation of malonate was found to be essential for a successful coupling. Synthetic potential of the obtained
Synthesis of fused indoline heterocycles via dearomatization of indoles with α-bromohydrazones: a systematic study on the substrates
作者:Wen-Bin Cao、Xiao-Ping Xu、Shun-Jun Ji
DOI:10.1039/c6ob02362b
日期:——
An efficient metal-free dearomatization of indoles with α-bromohydrazones is reported. Various fused indoline heterocycles, which are potentially biologically active, were achieved in good yields (up to 94%) under mild conditions. A systematic study on electronic- and steric effects of substrate and reagents revealed that they have great influence upon the reaction. Based on this, the scope of indoles