In this paper, used cheap, easy?to?obtain and multi?reactive 2?position single?side chain substituted 1,3?cyclohexanedione compound as a synthetic building block, used phenyl tetrafluoroborate diazonium salt as raw material, and adopt classic Japp?Klingemann fischer indole synthesis method, it is ring?opening fragmentation and following ring?closing to obtain more valuable multi?substituted indole structural units. Among them, 2?methyl?1,3?cyclohexidone and a diazonium salt of phenyl tetrafluoroborate were used as raw materials, under reflux conditions of p?toluenesulfonic acid as the acid reagent and toluene as the solvent, when the reaction was carried out for 15.0 h, the closed ring indole products were obtained with a yield of 49%; Meanwhile, 2?benzyl?1,3?cyclohexidone and a diazonium salt of phenyl tetrafluoroborate were used as raw materials, under the condition of heating and refluxing in a sealed tube of 30% hydrochloric acid ethanol solution, when the reaction was carried out for 0.5 h, the closed ring indole products were obtained with a yield of 98%. This methodology can be applied to the total synthesis of indole alkaloids.