Synthesis and characterization of lithocholic acid derived dipyrromethanes: Precursors for pyrrole-steroidal macrocycles

Article abstract of DOI:10.1016/j.molstruc.2004.02.014

Three steroidal dipyrromethanes, 3,3,24,24-tetrakis(pyrrol-2-yl)-5β- cholane 1, 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oic acid 2, and methyl 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oate 3, have been prepared from 3α-hydroxy-5β-cholan-24-oic acid (lithocholic acid) 4 in good overall yields. The structures of 1-3 have been fully characterized by ¹H, ¹³C, PFG DQF ¹H-¹H COSY, ¹H- ¹H ROESY, ¹³C DEPT-135, PFG ¹H-¹³C HMQC, PFG ¹H-¹³C HMBC, and PFG ¹H- ¹⁵N HMBC NMR spectra. Their molecular weights and compositions have been determined by ESI-TOF and EI mass spectra, and elemental analyses. The energetically optimised geometry and isotropic ¹³C NMR chemical shifts of 3,3,24,24-tetrakis(pyrrol-2-yl)-5β-cholane 1 have been calculated by ab initio HF/6-31G* and DFT B3PW91/6-311G* methods.