Oxocarbons and Related Compounds; Part 17.1 3-Chloro-3-cyclobutene-1,2-dione, a Highly Reactive Dienophile; Simple Synthesis of Bicyclo[4.2.0] octa-1(6),3-diene-7,8-diones and Benzocyclobutenediones 3-Chloro-3-cyclobutene-1,2-dione (1c) reacts with the dienes 3a-e on careful heating to 110°C to afford the bicyclo[4.2.0]octa-1(6), 3-diene-7,8-diones 4a-e. The reaction pathway is explained by Diels-Alder adduct formation and subsequent elimination of hydrogen chloride. 4a-e are readily oxidized by activated manganese(IV) oxide to give the benzocyclobutenediones 5a-e in good yields. The parent benzocyclobutenedione (5a) has been prepared even more conveniently in a "one-pot" Diels-Alder route by heating a mixture of 3-Chloro-3-cyclobutene-1,2-dione (1c) and 1-acetoxy-1,3-butadiene (3f).
碳氢化合物及相关化合物;第 17.1 部分 3-
氯-
3-环丁烯-1,2-二酮,一种高反应性亲双烯体;双环[4.2.0]八-1(6),3-二烯-7,8-二酮和
苯并环丁烯二酮的简单合成 3-
氯-
3-环丁烯-1,2-二酮 (1c) 与二烯 3a-e 反应小心加热至110°C,得到双环[4.2.0]octa-1(6), 3-二烯-7,8-二酮4a-e。该反应途径通过狄尔斯-阿尔德加合物的形成和随后
氯化氢的消除来解释。 4a-e很容易被活化的
氧化锰(IV)氧化,以良好的收率得到
苯并环丁烯二酮5a-e。母体
苯并环丁烯二酮 (5a) 可以通过加热 3-
氯-
3-环丁烯-1,2-二酮 (1c) 和 1-乙酰氧基-1 的混合物,以“一锅法”Diels-Alder 路线更方便地制备。 ,3-
丁二烯(3f)。