An investigation of the scope of the 1,7-electrocyclization of α,β:γ,δ-conjugated azomethine ylides
摘要:
Substituents on the diene component have little influence on the periselectivity of the cyclizations of alpha,beta:gamma,delta-conjugated azomethine ylides, with 1,7-electrocyclizations predominating. In some cases, subtle changes to these substituents can, however, influence the product formed, through their effect on the relative energies of the transition states for the 1,5- (6 pi) and 1,7-electrocyclization (8 pi) processes. The most striking changes in periselectivity occur for phenylethenyl-substituted azomethine ylides 3d-f, which can give either a pyrroline 4d,f or dihydrobenzazepine 6e, depending upon the alkene configuration. (C) 2014 Elsevier Ltd. All rights reserved.
Phosphazene base-catalyzed hydroamination of aminoalkenes for the construction of isoindoline scaffolds: Application to the total synthesis of aristocularine
A method for isoindoline synthesis via phosphazene base-catalyzed intramolecular hydroamination of aminoalkenes was developed. The reaction has a broad functional group tolerance, including for halide, cyano, and methoxy groups, and could also be used to synthesize tetrahydroisoquinoline, pyrrolidine, and piperidine. The method was used as a key step in the total synthesis of aristocularine in six
建立了磷腈碱催化氨基烯烃分子内加氢胺化合成异二氢吲哚的方法。该反应具有广泛的官能团耐受性,包括卤化物、氰基和甲氧基,也可用于合成四氢异喹啉、吡咯烷和哌啶。该方法被用作马兜铃碱全合成的关键步骤,分六步进行,总产率为 35%。该策略涉及通过控制所需 C N 键的形成来构建异二氢吲哚核心,而相对不稳定的甲氧基甲基和芳基溴保持完整。
Iodine‐Catalyzed Cascade Reaction of 2‐Styrylbenzaldehydes with Indoles in the Synthesis of 1<i>H</i>‐Indenes via 4π‐Electrocyclization
作者:Sundaram Suresh、Hao‐Yu Tsai、Xin‐Lun Han、Veerababurao Kavala、Sowndarya Palla、Ching‐Fa Yao
DOI:10.1002/adsc.202301412
日期:2024.3.19
A cascade reaction between 2-styrylbenzaldehydes and indoles has been developed for the synthesis of 1H-indenes. An iodine-catalyzed nucleophilic addition of indoles to an aldehyde group of 2-styrylbenzaldehydes leads to the formation of carbocation intermediates that undergo 4π-electrocyclization to give indenes with a trisubstituted double bond. These indenes are transformed into thermodynamically