Indoline spiropyrans containing benzo[f]coumarin moiety annulated to the 2H-pyran cycle were synthesized. The obtained compounds exist in solutions as a tautomeric mixture of their spirocyclic and merocyanine forms. The spiro form exhibits an enhanced resistance to UV irradiation and does not rearranges into the merocyanine isomer in the temperature range of 278–303 K.

中文翻译：

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基于苯并[f]香豆素的二氢吲哚螺吡喃的合成与结构

合成了含有与 2H-吡喃循环成环的苯并[f]香豆素部分的二氢吲哚螺吡喃。所得化合物以其螺环和部花青形式的互变异构混合物存在于溶液中。螺形式对紫外线照射具有增强的抵抗力，并且在 278-303 K 的温度范围内不会重新排列成部花青异构体。