| 摘要 |
Prepn. of triazine herbicides of formula (I): (where R' is 2-8C alkyl, 5-8C cycloalkyl, norbornyl, methylcyclohexyl, methylcyclopentyl, phenyl or chlorophenyl; R3 is Me; R4 is 1-4C alkyl) is by (a) treatingcyanamide with an alkyl chloroformate RO2C.Cl to give an alkoxycarbonylcyanamide; (b) treating the prod. with an alkylating agent CH3.Z to give an N-Alkoxy-carbonyl-N-methylcyanamide; (c) treating this cpd. with an amine salt of formula R3R4.NH2 +n.Yn-5 (where n is 1 when Y is Cl-; n is 2 when Y is SO4--) to give a cpd. of formula RO2CN(CH3)C(=NH2)NR3R4 + Yn-; (d) treating this cpd. with an alkali metal hydroxide to give a cpd. of formula: RO2CN(CH3)C(=NH)NR3R4; (e) removing unreacted amine R3R4NH; (f) treating the prod. from (d) with an isocyanate R1.NCO to give a cpd. RO2CN(CH3)C(=NCONHR') NR3R4; (g) treating the prod. with a base M1.OR5 to cyclise it and give (I). (where Z is Br, I or -O3S.OMe; M' is an alkali metal; R is 2-3 C alkyl, R5 is 1-4C alkyl). Process gives increased yields compared with the 5-s stage process of US 3850924, esp. when R is Et. In an example, 1a-methyl-4-cyclohexyl-6-dimethylamino-s-triazine-2, 4(1H,3H)dione was prepd. |
