Synthesis of (+)-thiersindole C

The indole diterpene alkaloid (+)-thiersindole C has been synthesised from ent-halimic acid. Firstly was elaborated the bicyclic system, secondly a Fischer indolization was used to obtain the north side chain and finally elongation of the south side chain was achieved with an isoprene unit. The synthesis of (+)-thiersin-dole C has corroborated the absolute configuration for the natural product (-)-thiersindole C. The synthesized (+)-thiersindole C showed antitumor activity against a number of human tumor cell lines with an lC(50) in the range of 10(-5) M.