A Simple, Effective, Green Method for the Regioselective 3-Acylation of Unprotected Indoles
作者:Phuong Tran、Hai Tran、Poul Hansen、Mai Do、Thach Le
DOI:10.3390/molecules201019605
日期:——
A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized.
An efficient and green method for regio- and chemo-selective Friedel–Crafts acylations using a deep eutectic solvent ([CholineCl][ZnCl<sub>2</sub>]<sub>3</sub>)
作者:Phuong Hoang Tran、Hai Truong Nguyen、Poul Erik Hansen、Thach Ngoc Le
DOI:10.1039/c6ra03551e
日期:——
and ZnCl2, has been used as a dual function catalyst and green solvent for the Friedel–Crafts acylation of aromatic compounds instead of using the moisture-sensitive Lewisacids and volatile organic solvents. The reactions are performed with high yields under microwave irradiation with short reaction times for the synthesis of ketones. Interestingly, indole derivatives are regioselectively acylated in
Boron Trifluoride Etherate Promoted Regioselective 3-Acylation of Indoles with Anhydrides
作者:Yunyun Zheng、Jiuling Li、Kai Wei
DOI:10.3390/molecules27238281
日期:——
An efficient, high-yielding and scalable procedure for the regioselective 3-acylation of indoles with anhydrides promoted by borontrifluorideetherate under mild conditions was reported. This novel protocol provided a simple way to prepare 3-(benzofuran-2-yl) indole in three steps.