A facile protocol for the unprecedented one-pot H2SO4-mediated hydroxymethylation/cyclative N,O-acetalization of 4-aminocoumarins to 1,4-dihydro-2H,5H-chromeno[4,3-d][1,3]oxazin-5-ones, in moderate to good yields, was developed and optimized. The scope and limitations of the transformation, which takes place in water or water/THF mixtures, were also studied. The nitrogen atom of the resulting tricycles was used to tether alkyl, aryl and 1,2,3-triazolylmethyl moieties, employing a two-step click chemistry approach for the latter. The photophysical properties of the heterocycles, as well as of their 1,2,3-triazole derivatives, were also examined. The N-aryl derivatives exhibited high quantum yields of fluorescence (up to Φf = 0.69) and very large Stokes shifts (up to 201 nm).
一种简便的方法用于将4-氨基香豆素经H2SO4介导的羟甲基化/环化N,O-缩醛化反应转化为1,4-二氢-2H,5H-色诺[4,3-d][1,3]噁唑啉-5-酮,产率中等至良好,已经开发并优化。还研究了该转化的范围和限制,该反应发生在水或水/THF混合物中。所得三环化合物的氮原子用于连接烷基、芳基和1,2,3-三唑基甲基基团,对后者采用两步点击化学方法。还研究了杂环化合物以及它们的1,2,3-三唑衍生物的光物理性质。N-芳基衍生物表现出高量子产率的荧光(高达Φf = 0.69)和非常大的斯托克斯位移(高达201 nm)。