| 摘要 |
<p>1374374 Isoxazolopyrimidines and their preparation FMC CORP 13 Oct 1972 [15 Oct 1971] 47240/72 Heading C2C Substituted isoxazolopyrimidines of the formula wherein R and R<SP>1</SP>, which may be the same or different, are straight or branched aliphatic hydrocarbon radicals having 1 to 4 carbon atoms may be obtained by reacting, in an acid medium, a 5-alkyl-3-amino-4-cyanoisoxazole of the formula with an acylating agent containing the radical R<SP>1</SP>-CO-. The acylating agent employed may be an acid chloride or anhydride and a suitable acid is sulphuric acid. The isbxazole starting materials may be obtained by reacting malononitrile with the appropriate trialkyl orthoalkanoate to give the corresponding 2-cyano-3- alkoxy-2-alkenenitrile, hydrolysing the latter to give the 2 - cyano - 3 - hydroxy - 2 - alkenenitrile (which may also be obtained by the reaction of malononitrile with the appropriate acid anhydride in the presence of potassium carbonate), treating the free hydroxy compound with PCl 5 to give the corresponding 3-chloro-2-cyano-2- alkenenitrile, and reacting the latter with N- hydroxyurea (prepared by the reaction of hy. droxylamine hydrochloride with ethyl carbamate in the presence of sodium hydroxide). The products possess herbicidal properties and may be formulated and applied in a conventional manner.</p> |
