2-substituted indole compound and preparation method thereof

The invention provides a 2-substituted indole compound. The compound is of a structure shown as a formula I, wherein R1 is selected from hydrogen, alkoxy, hydroxyl and halogen, and the position and the number of R1 cannot be fixed; R2 is selected from hydrogen, alkyl and C6 aryl; R3 is selected from a C6 aryl group, a C4-C8 heteroaryl group, a C1-C7 alkyl group, a C1-C6 cycloalkyl group, a C8 alkenyl group, a C4 ester group, and a trifluoromethyl group, and the C6 aryl group may have optionally one or more substitutions independently selected from the group consisting of hydrogen, C1 alkoxy, and halogen. The preparation method comprises the following steps: adding a compound shown as a formula A, a solvent, triphenylphosphine, an alkali and a compound shown as a formula B into a reaction flask at room temperature; putting the reaction system in the step (1) into an oil bath pan, uniformly stirring and reacting, and detecting a reaction endpoint by TLC; and taking out the reaction system in the step (2), separ