A facile synthesis of alkylated nitrogen heterocycles catalysed by 3D mesoporous aluminosilicates with cage type pores in aqueous medium
作者:Rajashree Chakravarti、Pranjal Kalita、S. Tamil Selvan、Hamid Oveisi、V. V. Balasubramanian、M. Lakshmi Kantam、Ajayan Vinu
DOI:10.1039/b914628h
日期:——
Friedel–Crafts alkylation of nitrogenheterocycles such as indoles and pyrroles with epoxides has been efficiently carried out using cage-type mesoporous aluminosilicates as recyclable catalysts in water under environmentally benign and mild conditions.
Fluoroboric acid adsorbed on silica gel catalyzed regioselective ring opening of epoxides with nitrogen heterocycles
作者:B.P. Bandgar、Abasaheb V. Patil
DOI:10.1016/j.tetlet.2006.10.118
日期:2007.1
Aryl epoxides can be opened in a regioselective and efficient manner with nitrogenheterocycles such as indoles, pyrroles and imidazoles in the presence of a catalytic amount of HBF4–SiO2 under mild conditions to afford the corresponding C-alkylated derivatives in good yields and with a high regioselectivity.
The reaction of epoxides with nitrogen heterocycles such as indoles, pyrroles, imidazoles, and pyrazoles was studied under both high-pressure and silica gel-catalyzed conditions. Whereas it has been reported that the treatment of indole with styrene aside at in kbar and 42 degrees C for 24 h gave 2-(3-indolyl)-2-phenylethanol in 56% yield, the same compound was obtained in 88% yield when the reaction was conducted on silica gel at rt for 1 week. Similarly, efficient reaction of epoxides with pyrroles, imidazoles, and pyrazoles was achieved. In terms of stereochemical features, the epoxide ring opening reaction of (R)-(+)-styrene oxide with indole was found to proceed stereoselectively in an S(N)2 fashion at the benzyl carbon, in either ease.