4,5,6,7-Tetrahydroindoles, due to their easy aromatization, are good intermediates to synthesize indoles. 4,5,6,7-Tetrahydroindole on condensation with cyanoacetate leads to 1-ethylthio-2-cyano-4,5,6,7-tetrahydrocyclohexa-[c]-3H-pyrrolizin-3-one. Application 4,5,6,7-Tetrahydroindole was used as reactant in: synthesis of ethyl 3-(4,5,6,7-tetrahydroindol-2-yl)-2-propynoate preparation of BODIPY dyes N-alkylation with chloromethyloxirane preparation of hydroindolepropynoate by chemo- and regioselective solvent-free ethynylation palladium- and copper-free cross-coupling of halopropynoates preparation of carbonylalkenyl indoles via coupling with dicarbonyl compounds 1:2 annelation of 4,5,6,7-tetrahydroindole with 1-benzoyl-2-phenylacetylene