| 摘要 |
PURPOSE:To obtain the title compound which is used as a starting substance of agrochemicals and medicines by reducing a readily available 2H-1,4- benzoxazine-3(4H)-one derivative with sodium acyloxyborohydride. CONSTITUTION:The reduction of 2H-1,4-benzoxazine-3(4H)-one derivative of formula I (R<1>-R<3> are H, halogen, lower alkyl, lower alkoxy) with sodium acyloxyborohydride gives 3,4-dihydro-2H-1,4-benzoxazine such as 7-chloro-2H-1,4- benzoxazine-3(4H)-one. The compound of formula I is obtained by N- chloracetylation of an o-aminophenol derivative of formula III with chloracetyl chloride in the presence of a bicarbonate salt in dioxane followed by hydrogenation and thermal cyclization. The process of the present invention enables low- cost production of the title compound in high yield with high safety.
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