... Chemical When the crude products (1b–17b) were purified by col- umn chromatography, N-tert-butyl substituted benzamide by-products were also obtained (yield 10–15%), including N-tert-butyl benzamide, N-tert-butyl-4-fluoro-benzamide, N-tert-butyl-4 ... Canada 276 ... J. Chem. ...