Abstract: The invention relates to a process for the preparation of D-(+)-biotin, from a cysteine hydantoin of the formula I ##STR1## in which R.sup.1 is H, or a group R.sup.3 R.sup.4 CH-- or SiR.sup.5 R.sup.6 R.sup.7, in whichR.sup.3 and R.sup.4 in each case independently of one another are H, unsubstituted or substituted alkyl, cycloalkyl, aryl, aralkyl or heteroaryl or, taken together, are unsubstituted or substituted alkylene or heteroalkylene,R.sup.5, R.sup.6 and R.sup.7 in each case independently of one another are unsubstituted or substituted alkyl, cycloalkyl, aryl, aralkyl or heteroaryl,R.sup.2 is H or a protective group suitable for a nitrogen atom andX is O, S or N--R.sup.8, in whichR.sup.8 is an alkyl, cycloalkyl, aryl or alkoxycarbonyl group or a dialkylamino group and to intermediates which are passed through in this process.

Abstract: Indoloquinone compounds useful as cytostatic agents have formula (I), where R.sub.2 and R.sub.3 are in each case, hydrogen, halogen, an alkyl group (which may be substituted), an alkoxy group or an aryloxy group, an alkylthio group or an arylthio group, a primary or secondary amino group, hydroxy group or an amino group; R.sub.5 is hydrogen, a hydroxy group, an alkoxy group, an alkyl group (which may be substituted), or a carbohydrate moiety; R.sub.6 and R.sub.7 are in each case hydrogen, halogen, or an alkyl group; R.sub.8 is a group --CH.sub.2 X.sub.1, a group --CO.sub.2 --M.sup.+, where M.sup.+ is a metal ion; a group --CO.sub.2 R.sub.10, where R.sub.10 is hydrogen or an alkyl group (which may be substituted); a group --CONR'R", where R' and R" are hydrogen or alkyl groups (which may be substituted); R.sub.9 is a group --CR.sub.11 R.sub.12 X.sub.2, a group --CO.sub.2 --M.sup.+, where M.sup.+ is a metal ion; a group --CO.sub.2 R.sub.13, where R.sub.11, R.sub.12 and R.sub.