Basf Aktiengesellschaft

Hans-Joachim Opgenorth

Horst Scheuermann

Axel Nissen

Harald Laas

Wolfgang Schulte

Hans-Richard Mueller

A process for the preparation of an indolenine of the formula ##STR1## where R, X and Y are conventional substituents, by thermal rearrangement of a compound of the formula ##STR2## to give a compound of the formula ##STR3## and cyclization of this compound in the presence of an acid catalyst.

Preparation of indolenines

A process for the preparation of an indolenine of the general formula I ##STR1## where R, R.sup.1 and R.sup.2 are aliphatic radicals and R.sup.1 and R.sup.2 may also be linked and the ring A may be additionally substituted, wherein a compound of the formula II ##STR2## is heated in the presence of a Lewis acid and of a halide. The products are valuable starting compounds for the preparation of dyes.

Process for the production of benzothiazoles from N-arylsubstituted thioureas by oxidative ring closure characterized by the use of chlorine as oxidizing agent and by the presence of catalytic amounts of bromine. Yield and quality of the benzothiazoles obtained are very good.

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Frankenthal, Germany

Hans-Joachim Opgenorth