1374690 Isoihiazolopyrimidines and their preparation FMC CORP 13 Oct 1972 [15 Oct 1971] 47241/72 Heading C2C Substituted isothiazolopyrimidines of the formula wherein R and RSP1/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 (a) a 5 - alkyl - 3 - amino - 4 - cyanoisothiazole of the formula or (b) a 5 - alkyl - 3 - aminoisothiazole - 4- carboxamide of the formula in an acid medium with an acylating agent containing the radical RSP1/SP-CO-. The acylating agent employed may be an acid chloride or anhydride and a suitable acid is sulphuric acid. The starting materials may be obtained by reaction of methyl mercaptan and hydrogen chloride with the appropriate alkanenitrile, followed by thiohydrolysis in pyridine with hydrogen sulphide to yield the methyl dithioalkanoate, reaction of the latter with malononitrile to form the sodium salt of a 2-cyano-3- mercapto-2-alkenenitrile which is subsequently reacted with monochloramine; the 3-amino-4- cyano-5-alkylisothiazole obtained may be hydrolysed with concentrated H 2 SO 4 to yield the corresponding amide derivative. The products possess herbicidal properties and may be formulated and applied in a conventional manner.
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