3.6 g of ethyl 2-(4-bromo-2-chloro-benzoyl)-3-dimethylaminoacrylate (Example 13bk)) and 2-amino-2-methyl-1-propanol in 40 ml of 1,2-dichloroethane were stirred at room temperature for 1 hr. with the direct introduction of argon. Then, 0.74 ml of triethylamine, 1.66 g of tert.-butyldimethylchlorosilane and 1.22 mg of 4-dimethylaminopyridine were added and the mixture was stirred at room temperature for 24 hrs. The reaction mixture was chromatographed directly on silica gel in dichloromethane. 4.64 g (92%) of ethyl 2-(4-bromo-2-chloro-benzoyl)-3-[2-(tert.-butyl-dimethyl-silanyloxy)-1,1-dimethyl-ethylamino]-acrylate were obtained as a colourless oil. Mass spectrum (ISP): peaks inter alia at 520 (M+H, 100%), 518 (75%).
