一种新的萘并[1,2- b具有在4位酯取代基〕吡喃从2,3-二氢-2,2-二苯基-4-制备ħ -萘并[1,2- b ]吡喃-4-酮和然后转化为羧酸衍生物。通过紫外可见光谱研究了这两种化合物的光致变色行为,并通过NMR阐明了光产物的结构。在紫外线照射下,未着色的酯衍生物可提供具有反式-反式的单色着色的光异构体(TT)构型,同时将酸不可逆地转化为降解产物。在强酸介质中,两种化合物都转化为吡喃环开口形成的螺环衍生物,随后形成分子内内酯环并进行亲电芳族取代。
Thermally reversible photochromic behaviour of new naphthopyrans involving an intramolecular [2+2] cyclization reaction
作者:Paulo J. Coelho、Luís M. Carvalho、Gaston Vermeersch、Stephanie Delbaere
DOI:10.1016/j.tet.2009.04.070
日期:2009.7
New 4-(2,2-diphenylethenyl)naphthopyrans were synthesized and their photochromic behaviour in solution were studied under continuous UV light irradiation conditions. Although only one coloured photoproduct was expected to be formed, due to the naphthopyran substitution pattern, NMR analysis on degassed UV irradiated solutions, performed at low temperature, showed the formation of different compounds