Bolte M, Degen A, Egert E
Institut für Organische Chemie, Goethe-Universität Frankfurt, Marie-Curie-Strasse 11, 60439 Frankfurt/Main, Germany.
Acta Crystallogr C. 2000 Nov;56 Pt 11:1338-42. doi: 10.1107/s0108270100010131.
We have determined the crystal structures of bicyclo[2.2. 1]hept-2-ene-endo-cis-5,6-dicarboxylic anhydride, C(9)H(8)O(3), (I), 1,2,3,4,7,7-hexachlorobicyclo[2.2.1]hept-2-ene-endo-cis-5, 6-dicarboxylic anhydride diethyl ether solvate, C(9)H(2)Cl(6)O(3).0. 16C(4)H(10)O, (II), bicyclo[2.2.1]hept-2-ene-endo-cis-5, 6-dicarboxylic acid, C(9)H(10)O(4), (III), 1,2,3,4,7, 7-hexachlorobicyclo[2.2.1]hept-2-ene-endo-cis-5,6-dicarboxylic acid, C(9)H(4)Cl(6)O(4), (IVa) and (IVb), and ethyl 1,2,3,4,7, 7-hexachloro-6-carboxybicyclo[2.2. 1]hept-2-ene-endo-cis-5-carboxylate monohydrate, C(11)H(8)Cl(6)O(4). H(2)O, (V). Compounds (I) and (II) were prepared by a standard Diels-Alder reaction from maleic anhydride and cyclopentadiene or hexachlorocyclopentadiene, respectively. The crystal-growing processes of these compounds led to surprising results: rapid recrystallization of (I) from diethyl ether and (II) from petroleum ether gave crystals of these compounds, however, crystallization by slow evaporation techniques using common solvents yielded new compounds in which the five-membered heterocycle has been cleaved.
我们已测定了双环[2.2.1]庚-2-烯-内-顺-5,6-二羧酸酐（C₉H₈O₃，(I)）、1,2,3,4,7,7-六氯双环[2.2.1]庚-2-烯-内-顺-5,6-二羧酸酐二乙醚溶剂化物（C₉H₂Cl₆O₃·0.16C₄H₁₀O，(II)）、双环[2.2.1]庚-2-烯-内-顺-5,6-二羧酸（C₉H₁₀O₄，(III)）、1,2,3,4,7,7-六氯双环[2.2.1]庚-2-烯-内-顺-5,6-二羧酸（C₉H₄Cl₆O₄，(IVa)和(IVb)）以及1,2,3,4,7,7-六氯-6-羧基双环[2.2.1]庚-2-烯-内-顺-5-羧酸乙酯一水合物（C₁₁H₈Cl₆O₄·H₂O，(V)）的晶体结构。化合物(I)和(II)分别通过马来酸酐与环戊二烯或六氯环戊二烯的标准狄尔斯-阿尔德反应制备。这些化合物的晶体生长过程产生了令人惊讶的结果：(I)从二乙醚中快速重结晶以及(II)从石油醚中快速重结晶得到了这些化合物的晶体，然而，使用常用溶剂通过缓慢蒸发技术结晶得到了新的化合物，其中五元杂环已被裂解。
