| 摘要 |
9-(2,5-Dihalobenzyl) adenines substantially free of the 3-isomer, useful as coccidiostats, are prepared in a number of ways. One is by alkylating a salt of adenine with 3,6-dihalobenzyl halides in a two phase system in the presence of a phase transfer catalyst and then treating the resulting mixture of positional isomers, containing primarily the desired 9-isomer contaminated by substantial amounts of the mutagenic 3-isomer, by selectively dealkylating the 3-isomer with sulfuric acid in the presence of a carbenium ion trap to obtain the 9-isomer substantially free of the 3-isomer. Alternatively, 9-(2,6-dihalobenzyl)adenines are directly prepared uncontaminated with positional isomers from 4,5,6-triaminopyrimidine via 7-(N-formyl-N-dihalo-benzylamino) ¢1,2,5!thiadiazolo¢3,4-d!pyrimidine. |
