Org Lett. 2020 Aug 21;22(16):6248-6251. doi: 10.1021/acs.orglett.0c01912. Epub 2020 Aug 5.
Azanorbornadienes (ZNDs), prepared from pyrroles, undergo Michael reaction with thiols followed by retro-Diels-Alder (rDA) cleavage to release the starting pyrrole and a thiomaleate. Somewhat less reactive in this regard than furan-derived oxanorbornadienes, ZNDs have an additional point of variability at the pyrrole nitrogen center. Sulfonylated ZNDs were far more stable toward rDA cleavage than acylated analogues. -Butoxycarbonyl examples were much less reactive with thiols, rendering the rDA step slower than the initial conjugate addition.
氮杂降冰片二烯（ZNDs）可由吡咯制备，与硫醇发生迈克尔加成反应，然后进行逆狄尔斯-阿尔德（rDA）裂解，释放出起始吡咯和硫代马来酸酯。与呋喃衍生的氧杂降冰片二烯相比，ZNDs 的反应性略低，但在吡咯氮中心有另外一个可变性。磺酰化 ZNDs 比酰化类似物对 rDA 裂解更稳定。-丁氧基羰基的例子与硫醇的反应性要低得多，使得 rDA 步骤比初始的共轭加成慢。
