Novel Polycondensed Partly Saturated β-Carbolines Including Ferrocene Derivatives: Synthesis, DFT-Supported Structural Analysis, Mechanism of Some Diastereoselective Transformations and a Preliminary Study of Their in vitro Antiproliferative Effects.

Use of a Pictet-Spengler reaction of tryptamine and l-tryptophan methyl ester and subsequent reduction of the nitro group followed by further cyclocondensation with aryl aldehydes and formyl-substituted carboxylic acids, including ferrocene-based components, furnished a series of diastereomeric 6-aryl-substituted 5,6,8,9,14,14b-hexahydroindolo[2',3':3,4]pyrido[1-]-quinazolines and 5,5b,17,18-tetrahydroindolo[2',3':3,4]pyrido[1,2-]isoindolo[2,1-]quinazolin-11-(15b)-ones with the elements of central-, planar and conformational chirality. The relative configuration and the conformations of the novel polycyclic indole derivatives were determined by H- and C-NMR methods supplemented by comparative DFT analysis of the possible diastereomers. The structure of one of the pentacyclic methyl esters with defined absolute configuration "" was also confirmed by single crystal X-ray diffraction measurement.