PURIFICATION OF CRUDE 4-HYDROXYINDOLE

摘要

PURPOSE:To obtain high-purity 4-hydroxyindole in high yield, by subjecting crude 4-hydroxyindole prepared by oxidizing 4-oxo-4,5,6,7-tetrahydroindole to vacuum distillation at a specific temperature. CONSTITUTION:4-Oxo-4,5,6,7-tetrahydroindole shown by the formulaIis oxidized to give crude 4-hydroxyindole shown by the formula II, which is subjected to vacuum distillation at 100 deg.C- the melting point of the compound shown by the formulaI, preferably at 120-180 deg.C at 0.2-10mm.Hg, to give the high-purity compound shown by the formula II useful as a crude material for pindolol (beta- blocker agent) shown by the formula III in a yield of >=90% from the raw compound. Since a solvent is not required in this method, purificaion operations are simple, and there is no fear of the existence of a very small amount of a solvent in the final product without being removed.