A direct and mild strategy for the synthesis of benzo[a]azulenes based on an organocatalytic [10+4] cycloaddition reaction is described. The strategy enables a diversity-oriented approach for the synthesis of various poly-functionalised azulenes from easily accessible starting materials.
![Graphical abstract: Organocatalytic [10+4] cycloadditions for the synthesis of functionalised benzo[a]azulenes](http://hg.y866.cn/compound/lib/scimg/usr/1/C8CC08551J.jpg)
