Synthesis of dimethoxypyrimidines and uracils with novel C-5 substituents

摘要: 5-Iodo-2,4-dimethoxypyrimidine 1 on treatment with copper(I) 3-tetrahydropyran-2-yloxyprop-1-ynide was converted into 2,4-dimethoxy-5-(3-tetrahydropyran-2-yloxyprop-1-ynyl)pyrimidine 2 which toluene-p-sulphonic acid in methanol led to 5-(3-hydroxyprop-1-ynyl)2,4-dimethoxypyrimidine 3. This oxidised Swern reagent 5-(formylethynyl)-2,4-dimethoxypyrimidine 4. Compound 4 a number of Grignard reagents gave 5-[(3-alkyl or aryl-3-hydroxy)prop-1-ynyl]-2,4-dimethoxypyrimidines 6–12. These were 5-(acylethynyl)-2,4-dimethoxypyrimidines 13–19. On 6 mol dm–3 hydrochloric acid, 5-(2-acyl-l-chlorovinyl)uracils 20–23. Compounds 20–22 dehydrohalogenated sodium hydroxide 95% ethanol 5-(acylethynyl)uracils 24–26.