Ring contraction during the 6π-electrocyclisation of naphthopyran valence tautomers
作者:Christopher D. Gabbutt、B. Mark Heron、Suresh B. Kolla、Colin Kilner、Simon J. Coles、Peter N. Horton、Michael B. Hursthouse
DOI:10.1039/b807744d
日期:——
severe reaction conditions were required. The comparative ease of this rearrangement for the isomers and was rationalised on the basis of the relative isomer populations of the ring-opened naphthopyrans. The rearrangement of simple mono- and bis-methylsulfonylphenyl substituted photochromic naphthopyrans , was examined; the former failed to rearrange whereas the latter could be induced to rearrange only
螺(3H-萘并[2,1-b]吡喃-3,9'-噻吨-10,10-二氧化物)的热和光化学开环导致将环容易地收缩为9-(萘并[2, 1-b]呋喃-2-基)-9H-硫杂蒽-10,10-二氧化物。异构体螺(2H-萘并[1,2-b]吡喃-2,9'-噻吨并蒽-10,10-二氧化物)显示出相似的行为,提供9-(萘并[1,2-b]呋喃-2- yl)-9H-thioxanthene-10,10-dioxide,尽管需要更严格的反应条件。对于异构体,这种重排的比较容易,并且是根据开环萘并吡喃的相对异构体总体合理化的。检查了简单的单和双甲基磺酰基苯基取代的光致变色萘并吡喃的重排;前者不能重排,而后者只有在长时间的紫外线照射下才能被重排。