Anisole → 2-bromo-N'-methylbenzenesulfonimidamide

Participants

Reaction Steps

Cleavage of the tert-butyl group from 2-bromo-N-(1,1-dimethylethyl)-N'-methylbenzenesulfonimidamide by use of trifluoroacetic acid with or without added boron trifluoride etherate was found to be slow at room temperature. 2-Bromo-N-(1,1-dimethylethyl)-N'-methylbenzenesulfonimidamide (0.9 g, 2.9 mmol) recovered from these cleavage experiments and anisole (0.6 g, 5.5 mmol) were dissolved in trifluoroacetic acid (25 mL). Trifluoromethanesulfonic acid (ca. 9 g, 60 mmol) was added and the reaction mixture was stirred at room temperature for 1 hour. Then sodium acetate (5.5 g, 67 mmol) was added and the solvent was evaporated to leave a solid residue. This was dissolved in a mixture of dichloromethane and a small amount of water. Potassium carbonate was added until the mixture became basic. The mixture was partially dried (Na2SO4), filtered through Celite®, redried (Na2SO4), and gravity filtered. Evaporation of the solvent left a slightly brownish oil (1.4 g). This was dissolved in dichloromethane and chromatographed on a column of silica gel using 40:1 CH2Cl2 --Et2O followed by 1:1 CH2Cl2 --Et2O as eluant. Fractions containing the product (Rf =0.44, 10:1 CH2Cl2 --Et2O, UV) were evaporated to leave 2-bromo-N'-methylbenzenesulfonimidamide as a colorless oil (0.7 g.).

Provenance & Evidence