C3 prenylation/migration pathways are engaged in the reaction. Notably, this practical strategy can be applied to the late-stage diversification of tryptophan-based peptides and concise synthesis of tryprostatinB.
C 2烯丙基化的吲哚广泛存在于各种生物活性天然生物碱中。因此,将异戊二烯基选择性地安装在NH吲哚的C 2位置上具有重要意义。然而,已知的方案通常需要多步程序和化学计量的促进剂。在本文中,我们开发了通过酸催化使廉价的叔戊烯基醇对NH吲哚进行一步一步C2烯丙基化。其显着特征包括良好的区域选择性,阶跃和原子经济性,广泛的底物范围以及简单的催化体系。机理研究表明,C2异戊二烯化和C3异戊二烯化/迁移途径均参与了反应。值得注意的是,该实用策略可应用于色氨酸基肽的后期多样化和Tryprostatin B的简明合成。
Studies in the aza-Cope reaction: a formal highly enantioselective synthesis of tryprostatin B
作者:A Sofia Cardoso、Ana M Lobo、Sundaresan Prabhakar
DOI:10.1016/s0040-4039(00)00455-x
日期:2000.5
Studies in sigmatropic rearrangements of N-prenylindole derivatives ? a formal enantiomerically pure synthesis of tryprostatin B
作者:A. Sofia P. Cardoso、M. Manuel B. Marques、Natarajan Srinivasan、Sundaresan Prabhakar、Ana M. Lobo、Henry S. Rzepa
DOI:10.1039/b606457d
日期:——
Rearrangement of Na-prenyl-Nb-acetyltryptamine, induced by BF3·Et2O at low temperature, leads to a 2-prenyl derivative, and thence to the tricyclic tryptamine 7 and the indoline 8. Similarly, Na-prenyl-Nb-phthaloyl-L-tryptophan methyl ester furnished the corresponding 2-prenyl derivative 16, a known advanced precursor of tryprostatin B. Density functional (B3LYP) calculations for the putative rearrangement transition state for N-prenylskatole show that prior coordination of BF3 to the indolic nitrogen changes the character of the subsequent sigmatropic pericyclic shifts from being entirely covalent to acquiring a significant degree of ionic character. The shifting prenyl group favours the endo over the exo mode of the transition state by 4.1 kcal molâ1.