| 摘要 |
PURPOSE:A specific benzoxazine derivative is allowed to react with an acid halide and sulfuric acid to permit the high-yield production of the high-purity compound which is important as an intermediate of pyridobenzoxazine used as a medicine under mild conditions through simple operations. CONSTITUTION:The reaction between a benzoxazine derivative of formula I [R<1> is H, lower alkyl; X1, X2 are halogen; R<2> is formula II or III (R<3>, R<4>, R<5> are lower alkyl)], an acid halide such as acetyl chloride, propionyl chloride, n-butyrl chloride or benzoyl chloride and sulfuric acid of 90wt% or higher concentration, at a weight ratio of 1:(0.2-20):(0.1-5), preferably at room temperature to 150 deg.C for 5-120min to give a compound of formula IV (R<6> is H, lower alkyl).
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