Laccase-catalyzed domino reactions between hydroquinones and cyclic 1,3-dicarbonyls for the regioselective synthesis of substituted p-benzoquinones.
Laccase-catalyzed domino reactions between hydroquinones and cyclic 1,3-dicarbonyls for the regioselective synthesis of substituted p-benzoquinones.
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DOI：
10.1021/jo202082v
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发表时间：
2012-01
期刊：
影响因子：
--
通讯作者：
Szilvia Hajdok;J. Conrad;U. Beifuss
中科院分区：
文献类型：
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作者：
Szilvia Hajdok;J. Conrad;U. Beifuss
使用空气中的氧气作为氧化剂，通过漆酶催化的氢醌和环状 1,3-二羰基之间的多米诺反应，获得了高度取代的对苯醌，产率范围为 39% 至 98%。在几乎所有反应中，醌部分上具有两个相邻的 1,3-二羰基取代基的双加合物都是选择性形成的。该转化可以被视为多米诺氧化/1,4-加成/氧化/1,4-加成/氧化过程。以未取代的氢醌为底物，分离出2,3-二取代的对苯醌。双加合物也仅在与单取代的氢醌反应时形成。在几乎所有情况下都获得了2,3,5-三取代的对苯醌。当使用2,3-二取代的氢醌作为起始原料时，分离出2,3,5,6-四取代的对苯醌。所有产物的明确结构阐明均已通过 NMR 光谱方法实现，包括长程耦合 C=O 碳的自旋模式分析和 (1)H NMR 光谱中的 (13)C 卫星分析。
Highly substituted p-benzoquinones were obtained in yields ranging from 39% to 98% by laccase-catalyzed domino reactions between hydroquinones and cyclic 1,3-dicarbonyls using aerial oxygen as the oxidant. In almost all reactions bis-adducts with two adjacent 1,3-dicarbonyl substituents on the quinone moiety were formed selectively. The transformations can be regarded as domino oxidation/1,4-addition/oxidation/1,4-addition/oxidation processes. With unsubstituted hydroquinone as the substrate 2,3-disubstituted p-benzoquinones were isolated. Bis-adducts were also formed exclusively upon reaction with monosubstituted hydroquinones. In almost all cases the 2,3,5-trisubstituted p-benzoquinones were obtained. When 2,3-disubstituted hydroquinones were employed as starting materials the 2,3,5,6-tetrasubstituted p-benzoquinones were isolated. The unambiguous structure elucidation of all products has been achieved by NMR spectroscopic methods including spin pattern analysis of the long-range coupled C═O carbons and (13)C satellites analysis in (1)H NMR spectra.