Saccharin → 2-Methylbenzofuran-5-carbonitrile

Participants

Reaction Steps

2-Iodo-4-cynophenol (0.25 g, 1 mmol) and saccharin (0.1 g) in HMDSA (2 ml) was refluxed for 2 h under N2, until the solution became clear. The solvent was distilled off under reduced pressure and the residue was dissolved in anhydrous THF (2 ml). This was added to a solution made by mixing anhydrous ZnCl2 (0.3 g; 2.2 mmol) with 0.5 M 1-propynyl magnesium bromide in THF (7.8 ml) in anhydrous THF (5 ml) at room temperature under N2. To it, Pd (PPh3)4 (0.15 g) was added at room temperature under N2 followed by catalytic amount of CuI. The mixture was stirred at room temperature for 3 h and quenched with saturated NH4Cl solution. The mixture was diluted to 50 ml with EtOAc and washed with H2O. The organic layer was separated, dried over MgSO4 and filtered. The filtrate was evaporated and the residue was dissolved in 1,4-dioxane (4 ml) and 1 M TBAF in THF (0.3 ml) was added and this was stirred for 4 h at reflux. The solvent was distilled off and the residue was purified by FCC (SiO2, hexane/EtOAc) to give the title compound (0.145 g, 91%), as colourless solid. 1H-NMR (CDCl3) 7.78 (s, 1H); 7.46-7.44 (m, 2H); 6.41 (bs, 1H); 2.47 (s, 3H).

Provenance & Evidence