Process for producing staurosporine derivatives

A process for producing a staurosporine derivative represented by Formula (I):

• ##STR27## wherein:
• Q represents hydrogen or --X--(CH.sub.2).sub.m --Y--(CH.sub.2).sub.n --Z
• wherein:
• X represents a single bond or --CO--
• Y represents a single bond or --CH(OH)--
• Z represents hydroxy, O C O N R.sup.1 R.sup.2, in which each of R.sup.1 and R.sup.2 independently represents hydrogen or lower alkyl, or R.sup.1 and R.sup.2, combined together with the nitrogen atom adjacent thereto, form a heterocyclic group selected from the group consisting of pyrrolidinyl, imidazolidinyl, pyrazolidinyl, piperidino, morpholino, piperazinyl, N-methylpiperizinyl, indolinyl and isoindolinyl,
• carboxyl,
• N R.sup.3 and R.sup.4, in which each of R.sup.3 and R.sup.4 independently represents hydrogen or lower alkyl, or R.sup.3 and R.sup.4, combined together with the nitrogen atom adjacent thereto, form a heterocyclic group selected from the group consisting of pyrrolidinyl, imidazolidinyl, pyrazolidinyl, piperidino, morpholino, piperazinyl, N-methylpiperizinyl, indolinyl and isoindolinyl, or, aryl which is optionally substituted with 1 to 3 substituents independently selected from the group consisting of lower alkyl, lower alkoxy, amino, halogen and nitro,
• each of m and n independently represents an integer from 0 to 6,
• or a pharmaceutically acceptable salt thereof, which comprises oxidizing a compound represented by the formula (II) ##STR28## wherein Q has the same meaning as previously defined, with dimethylsulfoxide (DMSO) and an aqueous alkaline solution.