Cleavage of alkoxycarbonyl protecting groups from carbamates by t-BuNH2
作者:Oscar R. Suárez-Castillo、Luis Alberto Montiel-Ortega、Myriam Meléndez-Rodríguez、Maricruz Sánchez-Zavala
DOI:10.1016/j.tetlet.2006.11.024
日期:2007.1
An efficient, simple protocol for the selective cleavage of a variety of N-alkoxycarbonyl protectinggroups by t-BuNH2/MeOH is described. The scope of the procedure was explored for a series of indole, aniline and pyrrolidine carbamate derivatives containing other potentially reactive functional groups affording a clean cleavage of the carbamate group.
Aromatic Bromination versus Oxidation of Indolylmalonates by Bromine
作者:Martha S. Morales-Ríos、Norma F. Santos-Sánchez、Oscar R. Suárez-Castillo、Pedro Joseph-Nathan
DOI:10.1021/jo020543m
日期:2003.1.1
(2c), bromination at the 4- and 6-position is the dominating reaction. Investigation of the products composition of several 5-substituted indolylmalonates revealed the following trend: with a 5-substituted electron-withdrawing group like fluorine, the indolylmalonate undergoes oxidation rather than bromination. In contrast, with a 5-substituted electron-donating group, like a hydroxyl group, the ring
据报道,在NCl(4)或AcOH中,在N(1)位置带有吸电子基团的5-取代的吲哚基丙二酸酯(2a-e)与溴的反应。这些底物与众所周知的芳族溴竞争而发生氧化。在两组条件下,对于母体吲哚基丙二酸酯(2a),观察到化学特异性氧化,而对于5-羟基吲哚基丙二酸酯(2c),在4-位和6-位的溴化反应占主导。对几种5-取代的吲哚基丙二酸酯的产物组成的研究显示出以下趋势:对于具有5-取代的吸电子基团,如氟,吲哚基丙二酸酯进行氧化而不是溴化。相反,对于5-取代的供电子基团,如羟基,环溴化优先于氧化。当5-取代基为烷氧基时,获得大量的溴化氧化产物。通过质谱监测氧化反应允许表征2-溴吲哚基亚丙二酸酯中间体。溴离子被认为是该中间体形成中的可能途径。由(1)1 H NMR光谱,单晶X射线衍射和从头算来确定不对称的甲氧基和苄氧基取代基的构象。
Conformational studies of N-carbomethoxy-2-alkoxyindolenines by dynamic NMR, crystallography, and molecular mechanics
作者:Oscar R. Suárez-Castillo、Yaneth M.A. Contreras-Martínez、Lidia Beiza-Granados、Myriam Meléndez-Rodríguez、J. Roberto Villagómez-Ibarra、J. Martín Torres-Valencia、Martha S. Morales-Ríos、Pedro Joseph-Nathan
DOI:10.1016/j.tet.2005.07.023
日期:2005.9
and the transformation to their tautomeric indoles is reported. Variable-temperature 1H NMR studies of these 2-alkoxyindolenines evidenced dynamic processes involving two low-energy E and Z equilibrating conformers around the N–C(O) carbamate bond, for which the barriers (ΔG≠) between the two conformations are in the order of 12.5–13.9 kcal/mol, as deduced from computational NMR line shape simulations
报道了N-羰甲氧基-2-烷氧基吲哚烯的合成和向其互变异构吲哚的转化。这些2-烷氧基吲哚胺的可变温度1 H NMR研究表明,动态过程涉及围绕N–C(O)氨基甲酸酯键的两个低能E和Z平衡构象异构体,这两个构象之间的壁垒(ΔG ≠)为从NMR线形模拟计算得出,其数量级为12.5-13.9 kcal / mol。旋转势垒随着烷氧基基团的体积的增加而降低,其中E构象异构体总是更稳定。分子力学计算证明是首选准分子与X射线衍射研究一致,随着空间效应的增加,五元环中烷氧基的N轴位置。
Diastereoselective Indole-Dearomative Cope Rearrangements by Compounding Minor Driving Forces
作者:Subhadip De、Breanna M. Tomiczek、Yinuo Yang、Kenneth Ko、Ion Ghiviriga、Adrian Roitberg、Alexander J. Grenning
DOI:10.1021/acs.orglett.2c01381
日期:2022.5.27
Reported herein is the discovery of a diastereoselective indole-dearomative Coperearrangement. A suite of minor driving forces promote dearomatization: (i) steric congestion in the starting material, (ii) alkylidene malononitrile and stilbene conjugation events in the product, and (iii) an unexpected intramolecular π–π* stack on the product side of the equilibrium. The key substrates are rapidly assembled