Friedel–Crafts Hydroxyalkylation of Indoles Mediated by Trimethylsilyl Trifluoromethanesulfonate
摘要:
Indoles and N-alkylindoles undergo Friedel Crafts addition to aldehydes in the presence of trimethylsilyl trifluoromethanesulfonate and a trialkylamine to produce 3-(1-silyloxyalkyl)-indoles. Neutralization of the reaction mixture with pyridine followed by deprotection under basic conditions with tetrabutylammonium fluoride provides the 1:1 adduct as the free alcohol. This method prevents spontaneous conversion of the desired products to the thermodynamically favored bisindolyl(aryl)methanes, a process typically observed when indoles are reacted with aldehydes under acidic conditions.
An efficient and expedient approach for the synthesis of unsymmetrical 3,3′-Bis-indolylmethanes via silica gel-mediated Friedel-Craftsalkylation of 3-indolylmethanols with diverse indoles is described. The synthetic utility of this transformation was demonstrated by reusing silica gel up to 10 times without apparent loss of reactivity .
This work describes an efficient α-alkylation reaction of α-amino aldehydes with 3-indolylmethanols. In the promotion of catalyst 3f, the target products were obtained in high yields (up to 99%), good diastereoselectivities (up to 88:12), and excellent enantioselectivities (up to 96% ee). The direct alkylation products can be readily converted into other tryptophan derivatives without the loss of stereoselectivities
Formal Asymmetric Organocatalytic [3+2] Cyclization between Enecarbamates and 3-Indolylmethanols: Rapid Access to 3-Aminocyclopenta[<i>b</i>]indoles
作者:Clément Lebée、Antti O. Kataja、Florent Blanchard、Géraldine Masson
DOI:10.1002/chem.201500749
日期:2015.6.1
A highly enantio‐ and diastereoselective synthesis of 3‐aminocyclopenta[b]indoles has been developed through formal [3+2] cycloaddition reaction of enecarbamates and 3‐indolylmethanols. This transformation is catalyzed by a chiral phosphoric acid that achieves simultaneous activation of both partners of the cycloaddition. Mechanistic data are also presented that suggest that the reaction occurs through
通过氨基甲酸酯和3-吲哚基甲醇的正式[3 + 2]环加成反应,已开发出高度对映体和非对映体选择性的3-氨基环戊[ b ]吲哚。该转化由手性磷酸催化,该手性磷酸实现了环加成的两个配偶体的同时活化。还提供了机理数据,表明该反应通过逐步途径发生。
Highly Enantioselective Alkylation Reaction of Enamides by Brønsted-Acid Catalysis
作者:Qi-Xiang Guo、Yun-Gui Peng、Jin-Wei Zhang、Liu Song、Zhang Feng、Liu-Zhu Gong
DOI:10.1021/ol901892s
日期:2009.10.15
The H-8-BINOL-derived, phosphoric acid catalyzed, highly enatioselective alkylation reaction of enamides with indolyl alcohols has been described. A phosphoric acid derived from H8-BINOL enabled an asymmetric alpha-alkylation of enamides with indolyl alcohols to give beta-aryl 3-(3-indolyl)propanones in high yields (up to 96%) and with excellent enantioselectivity (up to 96% ee).