发展了一种合成3，3-二氟-2-氧化吲哚及其衍生物的新方法。以简单的芳香胺和溴二氟乙酸乙酯为起始原料，在无溶剂和N2气保护下搅拌5 h，得到含二氟的氮乙酰苯胺衍生物中间体，产率85％～93％。该中间体与碘甲烷反应，得到N-甲基保护的乙酰苯胺衍生物，产率75％～90％。该衍生物在3.0化学计量促进剂次硫酸氢钠甲醛的存在下，以N，N-二甲基甲酰胺／H2 O为溶剂，发生分子内自由基关环反应，得到3，3-二氟-2-氧化吲哚及其衍生物，产率53％～72％。该方法原料便宜，不使用任何金属化合物，最后一步以水相为溶剂，较为环保，具有潜在的工业应用价值。
A novel method for the synthesis of 3,3-difluoro-2-oxindoles was developed .2-Bromo-2,2-difluoro-N-phenylacetamide was prepared from neat simple aromatic amines with ethyl bromodifluoroacetate .Reflux of the product in CH3CN with CH3I for 24 h gave 2-bromo-2,2-difluoro-N-methyl-N-phenylacetamide in 75%~90% yields. In the presence of 3.0 chemometric number sodium formaldehyde sulfoxylate , this key intermediate undergoes intramolecular radical cyclization in aqueous solution ( N,N-dimethylformamide/H2 O) and affords the final product 3,3-difluoro-1-methylindolin-2-ones in 53%~72% yields.This method can be performed in aqueous solution from commercially available and affordable starting materials without any metal catalysts.It shows potential in industrial production of 3,3-difluoro-2-oxindoles.
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