申请人:Warner-Lambert Company
公开号:US03960856A1
公开(公告)日:1976-06-01
An improved process for the preparation of 4-hydroxy-3-(5-methyl-3-isoxazolylcarbamoyl)-2-methyl-2H-1,2-benzothiazine 1,1-dioxide (I), a known anti-inflammatory agent, requires the use of specific proportions of reactants and carefully controlled reaction conditions. An alkali metal alkoxide, suspended in dimethylformamide is combined, with stirring, as rapidly as possible with a solution of alkyl 2,3-dihydro-3-oxo-1,2-benzisothiazole-2-acetate 1,1-dioxide (II) in dimethylformamide, while maining the internal reaction temperature within 15.degree.-30.degree.C. More than two but less than six moles of the alkoxide are used per mole of the alkyl 2,3-dihydro-3-oxo-1,2-benzisothiazole-2-acetate 1,1-dioxide (II). After all reactants have been combined, stirring is continued for a specific period of time and then the reaction mixture is acidified. Total elapsed time from initial combination of reactants to acidification is from 30 to 50 minutes. Acidification of the reaction mixture precipitates out alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide (III) in substantially pure form in high yields, without recrystallization. Product III is methylated on the sulfonamide nitrogen and reacted with 3-amino-5-methyl-isoxazole to obtain crude I. A further improvement in the process of the invention involves a more efficient method for purifying crude product I: the need for large quantities of dioxane solvent is obviated. After slurrying and washing, product I is solubilized in dilute alkali, and decolorized. After filtration and acidification pure product I in high yield is obtained. In addition to preparing the known anti-inflammatory agent (I), the initial reaction step of the invention wherein 2,3-dihydro-3-oxo-1,2-benzisothiazole-2-acetate, 1,1-dioxide (II) is rearranged to form alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide (III), may be used with particular advantage for the preparation of other useful benzothiazine derivatives.
一种改进的制备4-羟基-3-(5-甲基-3-异噁唑基甲酰基)-2-甲基-2H-1,2-苯并噻嗪-1,1-二氧化物(I),一种已知的抗炎药物的过程,需要使用特定比例的反应物和精确控制的反应条件。在二甲基甲酰胺中悬浮的碱金属烷氧化物与二甲基甲酰胺中的烷基2,3-二氢-3-酮-1,2-苯并噻嗪-2-乙酸酯1,1-二氧化物(II)的溶液迅速混合,并在保持内部反应温度在15度至30度之间的情况下搅拌。每摩尔烷氧化物使用两个以上但少于六个摩尔的烷基2,3-二氢-3-酮-1,2-苯并噻嗪-2-乙酸酯1,1-二氧化物(II)。在所有反应物混合后,继续搅拌一段特定时间,然后将反应混合物酸化。从初始混合反应物到酸化的总经过时间为30至50分钟。酸化反应混合物使烷基4-羟基-2H-1,2-苯并噻嗪-3-羧酸酯1,1-二氧化物(III)以高收率的基本纯形式沉淀出来,无需再结晶。产品III在磺胺酰氮上甲基化,并与3-氨基-5-甲基-异噁唑发生反应,得到粗I。发明的过程中的进一步改进涉及一种更有效的精制粗产品I的方法:无需大量二噁烷溶剂。在搅拌和洗涤后,产品I在稀碱中溶解,并脱色。经过过滤和酸化后,高收率得到纯产品I。除了制备已知的抗炎药物(I)外,发明的初始反应步骤中,其中2,3-二氢-3-酮-1,2-苯并噻嗪-2-乙酸酯,1,1-二氧化物(II)被重新排列以形成烷基4-羟基-2H-1,2-苯并噻嗪-3-羧酸酯1,1-二氧化物(III),可能特别有利于制备其他有用的苯并噻嗪衍生物。