Regioselective ethoxy-carbonylation of indoles and indazoles using DEAD and tetraethylammonium cyanide

Samikannu Ramesh, Pirama Nayagam Arunachalam, Appaswami Lalitha
2013 RSC Advances  
General procedure: Under nitrogen atmosphere, a reaction flask charged with indole or indazole (0.2 mmol), a tetraethyl ammonium cyanide (0.4 mmol), a and aectonitrile (2 mL) was cooled to 0 °C and DEAD (0.4mmol) a was added slowly (dropwise) at this temperature. After the addition, reaction mass was slowly warmed to RT and at RT the reaction mass was stirred for 12hduring while the reaction was monitored by TLC. After the completion of the reaction , 10 mL of ethylacetate was added and the
more » ... ure was washed with water (3×5 mL). Then the organic layer was concentrated in vacuum and the residue was purified by flash column chromatography on a silica gel to give the desired product. Thin layer chromatography was performed on silica gel plates. Silica gel (Merck, 230-400 mesh) was used for flash column chromatography. 1 H and 13 C NMR spectra were recorded on a Bruker (400 MHz) spectrometer and the COSY spectra were recorded on a Varian (500MHz) spectrometer. Chemical shift values (δ) are given in ppm and are referenced to residual solvent peaks ( 1 H and 13 C NMR). Coupling constants (J) were reported in hertz (Hz). Mass spectra and high resolution mass spectra (LC-MS) were also reported. X-ray crystal structure was obtained by Bruker CCD area detector diffractometer. a (For nitro subsituted indole or indazole, the reaction mixture composition was as follows : indole/indazole (0.2 mmol), tetraethyl ammonium cyanide (0.6 mmol), DEAD (0.6 mmol)) Electronic Supplementary Material (ESI) for RSC Advances This journal is
doi:10.1039/c3ra40972d fatcat:cs4m37bexfebranvz6vxacvif4