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Synthesis and reactivity of photochromic 2H-chromenes based on 3-carboxylated c...
Cerqueira, N. M. F. S. A.; Rodrigues, Lígia M.; Campos, Ana M. F. Oliveira; Carvalho, Luís H. Melo de; Coelho, Paulo J.; Dubest, Roger; Aubard, JeanNew photochromic 2H-chromenes including a 3-carboxylated coumarin nucleus were synthesised from hydroxycoumarins, and, in one case, the corrresponding trimethoxysilylcarboxamide was prepared. The photochromic behaviour 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...
Synthesis and photochromic behaviour of new methyl induced linear and angular t...
Queiroz, Maria João R. P.; Plasencia, Paula M. S.; Dubest, Roger; Aubard, Jean; Guglielmetti, Robert J.New methyl induced linear and angular thieno-2H-chromenes 4, 5 and 6 were prepared by reaction of new methylated 6-hydroxybenzo[b]thiophenes 2 (a, b and c) and propargylic alcohols 3a and 3b, using acidic Alumina Brockmann I as catalyst and drying agent. Compounds 2 were prepared in good to excellent yields in a “one pot” three step reaction from the corresponding bromo compounds 1. The photochromic behaviour ...
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