This invention relates to an improved method for the N-Carbomethoxylation of the 1, 3, 4 oxadiazines of formula (Ⅱ), and particularly Indoxacarb, using methyl chloro formate in the presence of sodium hydride resulting in compounds of formula (I) in which the ratio of the active S-isomer to the inactive R-isomer in the precursor can be retained. Ratios greater than or equal to 75% S-isomer, preferably greater than or equal to 99%, are achievable in the large scale manufacturing of the oxadiazines of formula (I) in the process.Wherein R1=F, Cl or C1-C3 fluroalkoxy, R2=C1-C3 linear or branched alkyl, or unsubstituted or hetero substituted aryl, R3=C1-C3 linear or branched alkyl, and R4=Trifluromethoxy, trifluromethyl, F, Cl or Br. The invention particularly relates to a process for the conversion of the compound of formula (Ⅱ) to the compound of formula (I) wherein R1=Cl, R2=CH3, R3=CH3and R4=OCF3, i.e. a process for the production of Indoxacarb.本發明係關於一種式(Ⅱ)之1,3,4-噁二嗪的N-甲氧羰基化作用(特別是因得克【Indoxacarb】)的改良方法,其係於氫化鈉存在下使用氯甲酸甲酯形成式(I)之化合物,其中於前驅物中之活性的S-異構物對不活性的R-異構物的比率可被保留。於此大批生產式(I)之噁二嗪的方法中,可達到大於或等於75%S-異構物,較佳的為大於或等於99%之比率。其中,R1為F、Cl或C1-C3之氟烷氧基;R2為C1-C3直鏈或支鏈烷基,或未經取代的或經雜取代的芳基;R3為C1-C3直鏈或支鏈烷基;及R4為三氟甲氧基、三氟甲基、F、Cl或Br。本發明特別是關於一種由式(Ⅱ)的化合物轉化成式(I)的化合物,其中R1為C1,R2為CH3,R3為CH3,及R4為OCF3,即一種生產因得克的方法。
