Thermal reaction of electron deficient 4-oxo-4<i>H</i>
-pyrazole 1,2-dioxide with cycloheptatriene: the first examples of the formation of an <i>endo</i>
-[4π + 6π]-cycloadduct and an intramolecular 1,3-dipolar reaction leading to a heterocage
作者:Koki Yamaguchi、Masashi Eto、Yasuyuki Yoshitake、Kazunobu Harano
DOI:10.1002/poc.3066
日期:2013.1
The reaction of 3,5‐bis(methoxycarbonyl)‐4‐oxo‐4H‐pyrazole 1,2‐dioxide (1a) with 1,3,5‐cycloheptatriene (2b) gave a mixture of the novel endo‐[4 + 6]‐cycloadduct (4ab), anti‐exo‐[4 + 2]‐cycloadduct (5ab), and the heterocage (6ab) derived from the intramolecular 1,3‐dipolar cycloaddition reaction of the syn‐endo‐[4 + 2]‐cycloadduct. Analogous endo‐[4 + 6] selectivity in 1,3‐dipolar cycloadditions has
3,5-双(甲氧羰基)-4-氧-4 H-吡唑1,2-二氧化物(1a)与1,3,5-环庚三烯(2b)的反应产生了新型内-[4 + 6] -cycloadduct(4AB),抗外切从的分子内1,3-偶极环加成反应得到的[4 + 2] -cycloadduct(5AB)和heterocage(6AB) -顺式-内- [4 + 2 ]-环加合物。以前没有报道过在1,3-偶极环加成反应中类似的内-[4 + 6]选择性。X射线分析表明6ab具有非常长的N sp3 –N s p3键距为1.617(4)Å。在理论上以B3LYP / 6-31G(d)水平优化的过渡态结构讨论了环加成反应的行为,据此可以预测周边选择性,区域选择性和立体选择性与实验结果吻合。版权所有©2012 John Wiley&Sons,Ltd.