CHEMISTRY OF O-BENZOQUINONES AND MASKED O-BENZOQUINONES .3. DIELS-ALDER REACTIONS OF 6,9-DIPROPYL-1,4-DIOXASPIRO[4.5]DECA-6,8-DIENE-2,10-DIONE WITH SUBSTITUTED ALKENES - AN ENTRY TO BICYCLO[2.2.2]OCT-5-ENE-2,3-DIONES AND 1,3-CYCLOHEXADIENES
CHEMISTRY OF O-BENZOQUINONES AND MASKED O-BENZOQUINONES .3. DIELS-ALDER REACTIONS OF 6,9-DIPROPYL-1,4-DIOXASPIRO[4.5]DECA-6,8-DIENE-2,10-DIONE WITH SUBSTITUTED ALKENES - AN ENTRY TO BICYCLO[2.2.2]OCT-5-ENE-2,3-DIONES AND 1,3-CYCLOHEXADIENES
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DOI：
10.1002/jccs.198400009
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发表时间：
1984-01-01
影响因子：
1.8
通讯作者：
UANG, BJ
中科院分区：
文献类型：
--
作者：
HSU, YH;KUO, LC;UANG, BJ
研究了标题化合物 1，掩蔽的 3, 6-二丙基邻苯醌与各种双取代（马来酸二乙酯、富马酸二乙酯、反式和顺式二苯乙烯和环庚烯）和单取代烯烃（丙烯酸甲酯、甲基乙烯基酮、苯乙烯、乙基乙烯基醚和 1-己烯）的环加成反应；除二苯乙烯外，第尔斯-阿尔德加合物 2 的产率通常很高（> 75%）。这些加合物有效地转化为相应的双环[2.2.2]oct-5-ene-2, 3-二酮, 3，其立体化学是根据各自喹喔啉 4 的环电流效应对乙烯基和次甲基质子的化学位移和/或镧系元素 (Eu(fod)3) 诱导的相关质子 3 的位移来确定的。有趣的是，与 3 中相应质子的化学位移相比，喹喔啉环电流使乙烯基质子低场移动 0.15–0.27ppm，而喹喔啉部分的次甲基质子 (R3=H) 上场移动 0.18–0.39ppm。 α-二酮 3 转化为相应的 1, 3-环己二烯 5，通过使用海诺维亚中压灯通过铀玻璃过滤器进行的照射几乎是定量的。本研究为从儿茶酚viamaskedo苯醌制备双环[2.2.2]辛-5-烯-2, 3-二酮和1, 3-环己二烯提供了简便有效的方法。
The cycloadditions of the title compound, 1, a masked 3, 6‐dipropyl‐o‐benzoquinone to various disubstituted (diethyl maleate, diethyl fumarate,trans‐ andcis‐stilbene, and cycloheptene) and monosubstituted alkenes (methyl acrylate, methyl vinyl ketone, styrene, ethyl vinyl ether, and 1‐hexene) have been studied; the yields of the Diels‐Alder adducts, 2, are generally high (> 75%) except for stilbenes. These adducts are effectively transformed into the corresponding bicyclo[2.2.2]oct‐5‐ene‐2, 3‐diones, 3, whose stereochemistries are determined from the ring current effect of the respective quinoxalines, 4, on the chemical shifts of the vinyl and the methine protons and/or the lanthanide (Eu(fod)3) induced shift on the pertinent protons of 3. It is interesting to note that the quinoxaline ring current makes the vinyl protons down‐field shifted by 0.15–0.27ppmwhereas the methine protons (R3=H)synto the quinoxaline moiety up‐field shifted by 0.18–0.39ppmas compared to the chemical shifts of the corresponding protons in 3. The transformations of α‐diketones 3 into the corresponding 1, 3‐cyclohexadienes, 5, by irradition with a Hanovia medium pressure lamp through a uranium glass filter are almost quantitative. The present study provides facile and effective methods for the preparation of bicyclo[2.2.2]oct‐5‐ene‐2, 3‐diones and 1, 3‐cyclohexadienes from catecholsviamaskedo‐benzoquinones.