Report on an Unusual Cascade Reaction between Azulenes and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (=4,5-Dichloro-3,6-dioxocyclohexa-1,4-diene-1,2-dicarbonitrile; DDQ)
作者:Rolf Sigrist、Hans-Jürgen Hansen
DOI:10.1002/hlca.201000031
日期:——
The oxidation of 1‐(3,8‐dimethylazulen‐1‐yl)alkan‐1‐ones 1 with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (=4,5‐dichloro‐3,6‐dioxocyclohexa‐1,4‐diene‐1,2‐dicarbonitrile; DDQ) in acetone/H2O mixtures at room temperature does not only lead to the corresponding azulene‐1‐carboxaldehydes 2 but also, in small amounts, to three further products (Tables 1 and 2). The structures of the additional products
1-氧化(3,8- dimethylazulen -1-基)的烷-1-酮1与2,3-二氯-5,6-二氰基-1,4-苯醌(= 4,5-二氯3,室温下在丙酮/ H 2 O混合物中的6-二氧代环己基-1,4-二烯-1,2-二腈; DDQ)不仅会导致生成相应的azulene-1-甲醛2,而且还会少量生成3其他产品(表1和2)。通过X射线晶体结构分析(图1),用光谱法解析了其他产品3 – 5的结构,并使用光谱学方法解析了3a的结构。已证明双(氮杂烯基甲基)取代的DDQ衍生物5在甲醇分解或水解前体上产生产率,其在级联反应中在HCl损失下重排进入五环化合物3中(方案4和7)。发现的1,1'-[羰基双(8-甲基azulene-3,1-二基)]双[乙炔] 4是将Azulene-1-羧醛2进一步氧化为相应的Azulene-1-羧酸的结果(方案9和10)。