Cyclic Dienes. I. 1,2-Dimethylenecyclohexane1
Cyclic Dienes. I. 1,2-Dimethylenecyclohexane1
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环状二烯。
DOI：
10.1021/ja01115a048
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发表时间：
1953
影响因子：
15
通讯作者：
H. Golden
中科院分区：
文献类型：
--
作者：
W. Bailey;H. Golden
原子能委员会研究员，1949-1950年。由于有重新排列到内部位置的倾向，因此选择了一种不允许一个或两个双键迁移的合成方法。在烯烃合成过程中减少重排的可能步骤中，6选择了酯的热解，因为它简单。因此，以容易获得的邻苯二甲酸二乙酯（II）为起始原料，采用四步法合成I，总收率为77%。II在高压下与Raney镍加氢生成顺式和/反式六氢邻苯二甲酸二乙酯的混合物（III）。6Ill用LiAlH还原，产率高，生成六氢邻苯二醇（IV）。用10%盐酸酸化，再用乙醚穷举萃取是制备反应产物的理想方法。在硫酸用量为20%的条件下，循环醚V的收率为95%。IV是异构体的混合物，主要由顺式修饰组成，从中可以结晶出纯顺式形式或低熔融形式，mp43 -45。Adkins 7报道的六氢邻苯二醇（IVb）的反式或高熔融形式是先用NaOEt将III异构化为纯反式的Ilia，然后再用LiAlH还原。用乙酸酐回流得到六氢邻苯二甲酸酯(V)，通过300 × 25 mm的裂孔在510-520处裂解。由40摩尔%的I， 35摩尔%的醋酸烯烃VI和20%不变V组成的混合物，基于未回收的V和VI的环二烯I的收率为89%。以未回收的VI为基础，在近似相同的条件下，VI可以以90%的收率热解成I。
(3) AtomicEnergy Commission Fellow, 1949-1950. tendency to rearrange to an internal position, 4 a method of synthesis was chosen that did not permit migration of one or both of the double bonds. Of the possible procedures that minimize rearrangements during the synthesis of olefins, 6 the pyrolysis of an ester was selected because of its simplicity. Thus a four-step synthesis for I was developed in an over-all yield of 77% startingwith the readily available diethyl phthalate (II). II was hydro-genated with Raney nickel at high pressure to a mixture of cis-and/rans-diethyl hexahydrophthal-ate (III). 6Ill was reduced with LiAlH, in high yieldsto the hexahydrophthalyl alcohol (IV). A satisfactory method for working up the reaction product was acidification with 10% hydrochloric acid followed by exhaustive extraction with ether. In a run in which 20% sulfuric acid was used, a 95% yield of the cyclic ether V resulted. IV was a mixture of isomers consisting ofmostly the cis modification from which the pure cis form or low melting form, mp 43-45, could be crystallized. The trans modification, or high melting form of hexahydro-phthalyl alcohol (IVb), mp 55-56, that has been reported by Adkins, 7 was prepared by first isom-erizing III to the pure trans form Ilia with NaOEt before reduction with LiAlH,. Thehexahydro-phthalyl diacetate (V), obtained by refluxing IVwith acetic anhydride, was cracked at 510-520 through a 300 by 25-mm., helix-packed column to a mixture consisting of 40 mole% of I, 35 mole% of the olefin acetate VI and 20% unchanged V. The yield of the cyclic diene I based on unrecovered V and VI was 89%. VI can be pyrolyzed to I under ap-proximately the same conditions in 90% yields based on unrecovered VI.