An unequivocal proof of structure for the methoxychlorocyclopentanols (I′c–IV′c) was obtained by deetherification with 68% hydrobromic acid at 65–70°, followed by hydrogenolysis with Raney nickel and hydrogen, to the 1,2- and 1,3-cyclopentanediols, in the same manner as the methoxybromocyclohexanols (I–IV) were converted into the 1,2- and 1,3-cyclohexanediols. Hydrogenolysis of the methoxybromocyclohexanols and the methoxychlorocyclopentanols provided stereospeciflc syntheses for the cis- and trans-2- and -3-methoxycy-clohexanols and -cyclopentanols in 80–97% yields. Deetherification of the latter compounds with 68% hydrobromic acid gave the corresponding 1,2- and 1,3-cyclohexanediols and 1,2-cyclopentanediols in 70–90% yields, but only 5–7% yields of the 1,3-cyclopentanediols. For the proof of structure of methoxyhalocyclanols, deetherification should therefore precede, rather than follow, dehalogenation.
通过用65-70°的68%
盐酸脱醚化,然后用雷尼
镍和
氢气氢解,得到1,2-和
1,3-环戊二醇,可以明确证明甲氧基
氯环戊醇(I'c-IV'c)的结构,这与甲氧基
溴环己醇(I-IV)转化为1,2-和
1,3-环己二醇的方式相同。对甲氧基
溴环己醇和甲氧基
氯环戊醇进行氢解反应,可在80-97%的产率下合成顺式和反式2-和
3-甲氧基环己醇和
环戊醇。后者化合物用68%
盐酸脱醚化后,以70-90%的产率得到相应的1,2-和
1,3-环己二醇和
1,2-环戊二醇,但只有5-7%的产率得到
1,3-环戊二醇。因此,对于甲氧基卤代环烷醇的结构证明,脱醚化应该在去卤化之前进行,而不是之后。