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

摘要

Three steroidal dipyrromethanes, 3,3,24,24-tetrakis(pyrrol-2-yl)-5beta-cholane 1, 3,3-bis(pyrrol-2-yl)-5beta-cholan-24-oic acid 2, and methyl 3,3-bis(pyrrol-2-yl)-5beta-cholan-24-oate 3, have been prepared from 3alpha-hydroxy-5beta-cholan-24-oic acid (lithocholic acid) 4 in good overall yields. The structures of 1-3 have been fully characterized by H-1, C-13, PFG DQF H-1-H-1 COSY, H-1-H-1 ROESY, C-13 DEPT-135, PFG H-1-C-13 HMQC, PFG H-1-C-13 HMBC, and PFG H-1-N-15 HMBC NMR spectra. Their molecular weights and compositions have been determined by ESI-TOF and El mass spectra, and elemental analyses. The energetically optimised geometry and isotropic 13 C NMR chemical shifts of 3,3,24,24-tetrakis(pyffol-2-yl)-5beta-cholane 1 have been calculated by ab initio HF/6-31G* and DFT B3PW91/6-311G* methods. (C) 2004 Elsevier B.V. All rights reserved.