定义Definition
科普重排是 1,5-二烯在加热下发生 [3,3]-σ 迁移，异构化为另一个 1,5-二烯的协同周环反应。
The Cope rearrangement is the thermal [3,3]-sigmatropic isomerisation of a 1,5-diene into another 1,5-diene through a concerted pericyclic process.
机理Mechanism
经椅式（或船式）六元环过渡态，C3–C4 σ 键断裂、C1–C6 σ 键形成。反应可逆，平衡偏向热力学更稳定（取代更多、共轭或张力更小）的二烯。顺式-1,2-二乙烯基环丙烷因环张力释放而在低温即快速重排。
Through a chair (or boat) transition state the C3–C4 bond breaks and C1–C6 forms. It is reversible, favouring the more stable (more substituted, conjugated or less strained) diene; cis-1,2-divinylcyclopropane rearranges rapidly even at low temperature thanks to strain relief.
氧负离子科普重排Oxy-Cope variant
3-羟基-1,5-二烯重排后得烯醇，互变异构为羰基化合物使反应不可逆。其醇盐（KH/18-冠-6）重排速率加快 10¹⁰–10¹⁷ 倍（阴离子氧化科普，埃文斯 1975）。
3-Hydroxy-1,5-dienes give enols that tautomerise to carbonyls, making it irreversible; their alkoxides (KH/18-crown-6) rearrange 10¹⁰–10¹⁷ times faster (anionic oxy-Cope, Evans 1975).
由来与研究价值Origin and significance
美国化学家亚瑟·科普于 1940 年报道。瞬烯（bullvalene）分子中简并科普重排极快，使所有碳原子在室温下动态等价，是“流变分子”的著名例子。
Reported by Arthur Cope in 1940. In bullvalene, degenerate Cope rearrangements are so fast that all carbons become equivalent at room temperature — a famous fluxional molecule.
反应Reactions
150–300 °C 加热；阴离子氧化科普用 KH/18-冠-6，室温
Heat at 150–300 °C; anionic oxy-Cope with KH/18-crown-6 at room temperature
1,5-二烯采取椅式构象。
The 1,5-diene adopts a chair conformation.
协同断裂 C3–C4 并形成 C1–C6。
Concerted C3–C4 cleavage and C1–C6 formation.
简单的科普重排平衡。
A simple Cope equilibrium.
反应机理图Mechanism
红色弯箭头表示一对电子的移动方向：从电子来源（孤对电子或化学键）指向电子去向。Red curly arrows show where an electron pair moves: from its source (lone pair or bond) to its destination.
1,5-二烯的 [3,3] 迁移：σ 键在一端断开、另一端形成
[3,3] shift of a 1,5-diene: one σ bond breaks as another forms
平衡偏向取代更多的双键
The equilibrium favours the more substituted alkene
年表Timeline
- 1940
科普报道该重排
Cope reports the rearrangement
- 1963
德林预言、施罗德合成瞬烯（流变分子）
Bullvalene, predicted by Doering, is made by Schröder
- 1975
埃文斯报道阴离子氧化科普重排
Evans reports the anionic oxy-Cope