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本文报告烯酮(Ⅲ)的合成,与(Ⅲ)相当的烯醇体即1,2-二羟二环辛四烯(Ⅱ)。合成的关键中間物,二酮(Ⅳ),由一新合成步驟制备,总产率19—36％:低温加氯化氫于环戊二烯得3-氯环戊烯(85—92％),再用鎂使之双合而成二烯(Ⅴ)(80—92％)。(Ⅴ)的臭氧化合物經过氧乙酸分解而形成四元酸(Ⅵ),酯化后得其四甲酯(Ⅶ)(由(Ⅴ)至(Ⅶ)总产率66—75％);后者可环化为二甲氧羰基二酮(Ⅷ)(52—67％),(Ⅷ)經水解脫羧即生成二酮(Ⅳ)(79—84％)。二酮(Ⅳ)可还元为二醇(Ⅸ)(65％)。由二酮(Ⅳ)再經四步反应后即得烯酮(Ⅲ):氯化二酮(Ⅳ)得二氯二酮(Ⅹ)(64—74％);將(Ⅹ)与乙二醇一同脫水縮合得縮二酮(Ⅺ)(52—66％);自(Ⅺ)脫氯化氫后得二烯縮二酮(Ⅻ)(69％),后者与丙酮經交換反应即变为烯酮(Ⅲ)(76％)。上述各化合物的分子結構,均經証明。烯酮(Ⅲ)不含其相当的烯醇体(Ⅱ);在鹼性溶液中亦不能形成稳定的二环幸四烯二醇-陰离子。因此可以相信,二环辛四烯体系具有芳族性的可能性極微。
This paper reports the synthesis of enone (Ⅲ), which is equivalent to (Ⅲ) enol, namely 1,2-dihydroxybicyclooctate (Ⅱ). The key intermediate synthesized, diketone (IV), was prepared by a new synthetic procedure with a total yield of 19-36%: 3-chlorocyclopentene (85-92%) was obtained by adding hydrogen chloride to cyclopentadiene at low temperature, With magnesium so double into diene (Ⅴ) (80-92%). (V) is decomposed to form tetraacid (VI) by oxyacetic acid, then esterified to form tetramethyl ester (VII) (total yield of 66-75% from (V) to (VII) The cyclization to dimethoxycarbonyldiketone (Ⅷ) (52-67%), (Ⅷ) decarboxylation to generate dione (Ⅳ) (79-84%). Diketone (IV) may also be a diol (IX) (65%). The diketone (Ⅵ) (64-74%) is obtained from the diketone (IV) through another four steps reaction of the enone (III): diketone (IV) (XI) (52-66%); dehydrochlorination from (XI) gives the dienoyl ketone (XII) (69%), which is exchanged with acetone to give enone (III) (76%). The molecular structures of the above compounds have all been demonstrated. Enone (III) does not contain its equivalent enol (II); nor does it form stable bicyclic fortenediol-anions in alkaline solution. It is therefore believed that the possibility of the bicyclooctatetrane system being aromatic is minimal.