Effect of triplet-state sensitization on inter- and intramolecular 2+2 photocycloadditions of 2,5-cyclohexadien-1-ones
作者:Arthur G. Schultz、William Geiss
DOI:10.1021/ja00009a039
日期:1991.4
The intramolecular 2+2 photocycloadditions of 4-carbomethoxy-4-(4'-phenyl-3'-butenyl)-2,5-cyclohexadien-1-ones 5a, 5b, and 12 give 6-phenyltricyclo [5.2.1.0 1,10 ] dec-2-en-4-ones 6 and 13 in excellent yields. In contrasts to 4-(3'-butenyl)-4-carbomethoxy-3-methoxy-2,5-cyclohexadien-1-one (1), both 5a and 5b undergo photocyclization via triplet-state sensitization by Michler's ketone (MK). The mechanism
4-碳甲氧基-4-(4'-苯基-3'-丁烯基)-2,5-环己二烯-1-酮5a、5b和12的分子内2+2光环加成得到6-苯基三环[5.2.1.0 1, 10 ] dec-2-en-4-ones 6 和 13 的产率很高。与 4-(3'-butenyl)-4-carbomethoxy-3-methoxy-2,5-cyclohexadien-1-one (1) 相比,5a 和 5b 都通过米氏酮 (MK) 的三线态敏化进行光环化. 敏化光环化的机制必须涉及能量从 MK 转移到 5a 和 5b 中的苯乙烯发色团。茚与 4-carbomethoxy-3-methoxy-4-methyl-2,5-cyclohexadien-1-one (14) 的敏化分子间光加成产生至少八种环加合物。两个主要的环加合物(~60%)是反式融合的 16 和顺式融合的 17。