METHOD FOR PREPARING 4,5,6,7-TETRAHYDROINDOLE Russian patent published in 2007 - IPC C07D209/04 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to an improved method for synthesis of 4,5,6,7-tetrahydroindole. Method involves interaction of cyclohexanone oxime with acetylene under about atmospheric pressure, in dimethylsulfoxide medium, in the presence of a complex of sodium cyclohexane oximate with dimethylsulfoxide (DMSO) in the ratio 1:1 of the formula: as a catalyst. Catalyst is prepared by interaction of cyclohexanone oxime with sodium hydroxide in DMSO medium followed by azeotropic distillation of water formed wherein benzene, cyclohexane or toluene and, preferably, toluene is used as an azeotropic agent, and process is carried out at temperature 100-140°C. The end substance is isolated by distillation of the reaction mixture after its neutralization and dimethylsulfoxide and the crude end substance are separated followed by extraction of the crude substance in a two-phase system consisting of alkaline metal hydroxide aqueous solution and toluene as a hydrocarbon solvent. Method provides preparing the end product with the yield 94-97% and purity 99.1-99.3%.

EFFECT: improved method of synthesis.

8 cl, 6 sch, 11 ex