M. Queiroz, Paula M. S. Plasencia, R. Dubest
Mar 31, 2003
Citations
0
Influential Citations
10
Citations
Journal
Tetrahedron
Abstract
Abstract New methyl induced linear and angular thieno-2 H -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 of compounds 4 , 5 and 6b was evaluated with the aid of a classical set of spectrokinetic parameters, and compared to reference compounds that are benzoannellated in the 5,6 and 6,7 positions of the chromene (naphthopyrans) and also to thieno-2 H -chromenes 7 and 8 , previously prepared, which are analogues of 5a . The resistance to fatigue (photodegradation) under continuous irradiation was also evaluated.