反应详情

Schema 4 illustrates an alternative process for preparing the uracils of this invention in which a 7-amino-2,3-dihydrobenzofurnan, for example, 7-amino-4-chloro-2,3-dihydro-2,2-dimethylbenzofuran, is successively treated with trichloromethyl chloroformate and then ethanol to give the corresponding ethyl N-(2,3-dihydrobenzofuran-7-yl)carbamate (X). The carbamate is then reacted with sodium hydride and a 3-amino-3-fluoroalkylacrylate, for example, ethyl 3-amino-4,4,4-trifluorocrotonate, and subsequently with an alkyl iodide and potassium carbonate to produce the 3-(2,3-dihydrobenzofuran-7-yl)-1-alkyl-6-haloalkyluracil, for example, 3-(4-chloro-2,3-dihydro-2,2-dimethylbenzofuran-7-yl)-1-methyl-6-trifluoromethyluracil (VI). The 3-(2,3-dihydrobenzofuran-3-on-7-yl)-1-alkyl-6-haloalkyluracils of this invention may be prepared using an analogous method.