Synthesis and Reactivity of Photochromic 2H‐Chromenes Based on 3‐Carboxylated Coumarins |
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| Authors: | Nuno&#x M.&#x F.&#x S.&#x A. Cerqueira,Lí gia&#x M. Rodrigues,Ana&#x M.&#x F. Oliveira‐Campos,Luí s&#x H. Melo&#x de&#x Carvalho,Paulo&#x J. Coelho,Roger Dubest,Jean Aubard,Andr Samat,Robert Guglielmetti |
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| Affiliation: | Nuno M. F. S. A. Cerqueira,Lígia M. Rodrigues,Ana M. F. Oliveira‐Campos,Luís H. Melo de Carvalho,Paulo J. Coelho,Roger Dubest,Jean Aubard,André Samat,Robert Guglielmetti |
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| Abstract: | New photochromic 2H‐chromenes (=2H‐1‐benzopyrans) including a 3‐carboxylated coumarin nucleus were synthesized from hydroxycoumarins, and, in one case, the corresponding trimethoxysilylcarboxamide was prepared. The photochromic behavior was studied under flash‐photolysis conditions. The introduction of electron‐withdrawing substituents in this position of the coumarin nucleus led to a global and significant bathochromic shift in the spectra of the open forms and to an interesting intensification in the colorability. |
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