作者:Robert P. Claridge、Antony J. Deeming、Norman Paul、Derek A. Tocher、John H. Ridd
DOI:10.1039/a806451b
日期:——
The reaction of nitrogen dioxide with conjugated dienes (2,5-dimethylhexa-2,4-diene, hexa-2,4-diene and 2,3-dimethylbuta-1,3-diene) in organic solvents (mainly hexane, benzene and diethyl ether) results mainly in 1,4-addition giving, with the first two substrates, a mixture of 1,4-dinitro compounds and 1,4-nitro alcohols. The latter are presumably formed from hydrolysis of the intermediate nitronitrites. With 2,3-dimethylbuta-1,3-diene, only the cis and trans 1,4-dinitro compounds were isolated. The reactions effectively stop after the addition of two nitrogen dioxide radicals, only traces of tetrasubstituted products being obtained. With the unconjugated hepta-1,6-diene, addition can be made to occur to both double bonds but, when two equivalents of nitrogen dioxide are added very slowly, the main products derive from addition to one double bond and cyclisation to form cis and trans 1,2-bis(nitromethyl)cyclopentane. All the above reactions give a very complex mixture of products and the product composition depends markedly on the reaction conditions; however, with the conjugated dienes, the 1,4-dinitro compounds can be obtained in yields of ca. 50%. The crystal structure of trans-1,4-dinitro-2,3-dimethylbut-2-ene was determined.
二氧化氮与共轭二
烯(2,5-二
甲基己-
2,4-二
烯、己-
2,4-二
烯和2,3-二
甲基丁-1,3-二
烯)在有机溶剂(主要是己烷、
苯和二
乙醚)主要与前两种底物发生 1,4-加成反应,得到 1,4-二
硝基化合物和 1,4-硝基醇的混合物。后者可能是由
中间体亚硝酸盐的
水解形成的。对于2,3-二
甲基丁-1,3-二
烯,仅分离出顺式和反式1,4-二
硝基化合物。添加两个
二氧化氮自由基后,反应有效停止,仅获得痕量的四取代产物。对于非共轭 1,6-二
烯,可以对两个双键进行加成,但是,当非常缓慢地添加两当量的
二氧化氮时,主要产物源自对一个双键的加成和环化以形成顺式和反式1,2-双(硝基
甲基)
环戊烷。所有上述反应都会产生非常复杂的产物混合物,并且产物组成明显取决于反应条件;然而,使用共轭二
烯,可以以约1,4-二
硝基化合物的产率获得1,4-二
硝基化合物。 50%。测定了反式1,4-二硝基-2,3-二
甲基丁-2-
烯的晶体结构。