Bayer Aktiengesellschaft

Joachim Lanz

Ulrich Rosentreter

Paul Naab

Samir Samaan

The invention relates to new �3-amino!-tetrahydrocarbazole-propanoic acid esters which can be used as intermediates for the preparation of known thromboxane-antagonistic active compounds, and to a method for the purification of these active compounds.

�3-amino!-tetrahydrocarbazole-propanoic acid esters

(7-APCA) having the formula (I) ##STR1## which is an important synthesis intermediate in the preparation of cephalosporin-like antibiotics, is prepared by treating a compound of the formula (II) ##STR2## in which R.sub.1 and R.sub.2 represent alkyl, aryl and aralkyl radicals, with a strong protonic acid or with a Lewis acid. Compound (II) is prepared by adding triphenylphosphine and alkali metal iodide to a compound of the formula (VI) ##STR3## then reacting with acetaldehyde in base. Compound (VI) is prepared by treating a compound of the formula (VII) ##STR4## with a base in a polar solvent at -70.degree. C. to 0.degree. C. Compound (VII) is prepared by treating a compound of the formula (VIII) ##STR5## with a chlorinating agent in an organic solvent.

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Wuppertal, Germany

Joachim Lanz