参考路线如下：

In brief, 2,3,3‐trimethyl‐4,5‐benzo‐3H‐indole (TMBI, 10.0 g, 48 mmol) and alpha‐bromo‐p‐toluic acid (BTA, 12.3 g, 57 mmol) were dissolved in 40 mL dichlorobenzene and stirred under 110 °C for 4 h. The solid crude product was then filtrated and recrystallized in methanol. The purified product as denoted intermediate 1 was dried under vacuum.

80 mL DMF/dichloromethane mixture (1/1, v/v) was added dropwisely into a solution of phosphoryl chloride (37 mL) and anhydrous dichloromethane (35 mL) under stirring in ice/water bath; afterwards, 10 g cyclohexanone was added dropwisely. The ice/water bath was removed and the solution was then heated and refluxed for 3 h. The mixture was poured into ice, yielding a solid product which was collected by filtration and washed with iced diethyl ether. The resulting yellow product was denoted as intermediate 2 and used directly.

Intermediate 1 (1.64 g, 3.9 mmol) and intermediate 2 (0.34 g, 1.9 mmol) were mixed in 260 mL butanol/toluene (7/3, v/v), and stirred for 4 h under 115 °C. The solvent was removed by rotatory evaporation, and the crude product was purified by dissolving in DMF and precipitating in diethyl ether. After filtration, the product was dried under vacuum.