Surprising Formation of Highly Substituted Azulenes on Thermolysis of 4,5,6,7,8-Pentamethyl-2H-cyclohepta[b]furan-2-one and Heptalene Formation with the New Azulenes
作者:Vit Lellek、Hans-Jürgen Hansen
DOI:10.1002/1522-2675(20010613)84:6<1712::aid-hlca1712>3.0.co;2-e
日期:2001.6.13
e (1c) exhibit, on heating, such reactivity. However, heating of mixtures 1a/1b or 1a/1c results in the formation of crossed azulenes, namely 4,6,8-trimethyl-2-(2,3,4,5,6-pentamethylphenyl)azulene (4ba) and 2-(2,3,4,5,6-pentamethylphenyl)azulene (4ca), respectively (cf. Scheme 3). The formation of small amounts of 4,6,8-trimethylazulene (5ba) and azulene (5ca), respectively, besides 1H-indene 6a is
4,5,6,7,8-pentamethyl-2H-cyclohepta[b]furan-2-one (1a) 在十氢化萘中的加热温度 > 170° 导致蓝色的发展,这是典型的 azulenes。事实上,它属于两种形成的薁,即 4,5,6,7,8-pentamethyl-2-(2,3,4,5,6-pentamethylphenyl)azulene (4a) 和 4,5,6,7 ,8-五甲基薁 (5a)(参见方案 2 和表 1)。作为第三种产物,4,5,6,7-四甲基-2-(2,3,4,5,6-五甲基苯基)-1H-茚(6a)也存在于反应混合物中。4,6,8-trimethyl-2H-cyclohepta[b]furan-2-one (1b) 和 2H-cyclohepta[b]furan-2-one (1c) 在加热时都没有表现出这种反应性。然而,加热混合物 1a/1b 或 1a/1c 会导致形成交叉的薁,即