Further studies of the thermal and photochemical Diels-Alder reactions of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with naphthalene and some substituted naphthalenes
Further studies of the thermal and photochemical Diels-Alder reactions of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with naphthalene and some substituted naphthalenes
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DOI：
10.1021/jo9906429
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发表时间：
2000-05-19
影响因子：
3.6
通讯作者：
Newton, KA
中科院分区：
文献类型：
--
作者：
Breton, GW;Newton, KA
甲缩醛与萘（2）和甲基化萘进行热反应，得到起始原料和[4 + 2]环加合物的平衡混合物。萘环上的甲基取代通常增加了相对于2的环加成物形成的量和环加成速率。分离的环加合物都是热不稳定的，并在2，3-二甲基-2-丁烯的存在下定量地还原为母体萘，作为释放的MeCl 4的陷阱。环化反应的速率受取代模式的影响，但不明显的溶剂。环加成反应的一种机制，提出了参与的电荷转移复合物。在光化学反应中，MeCl 4与取代萘的反应相对于相应的热反应表现出较低的区域选择性。
MeTAD thermally reacted with naphthalene (2) and methylated naphthalenes to give equilibrium mixtures of starting materials and [4 + 2] cycloadducts. Methyl substitution on the naphthalene ring generally increased both the amount of cycloadduct formed and the rate of cycloaddition relative to 2. The isolated cycloadducts were all thermally labile and quantitatively reverted to the parent naphthalene in the presence of 2,3-dimethyl-2-butene as a trap for liberated MeTAD. The rates of the cycloreversion reactions were affected by substitution patterns but not appreciably by solvent. A mechanism for the cycloaddition reaction is presented that proposes the involvement of a charge-transfer complex. Photochemically, MeTAD demonstrated lower regioselectivity in its reactions with substituted naphthalenes relative to the corresponding thermal reactions.