Improved preparation and structural elucidation of the tryptophan cleavage reagent 2-(2'-nitro-phenylsulfenyl)-3-methyl-3-bromoindolenine (BNPS-skatole).

Methods are described for a high yield preparation (overall yield greater than 90%) of analytically pure 2-(2'-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine (BNPS-skatole). The chromatographic and spectroscopic data are given. The yield of tryptophan cleavage is considerably dependent on the degree of purity of the BNPS-skatole.