Synthesis of Biliverdins with Stable Extended Conformations. Part II.

BARI, SARA E.; ITURRASPE, JOSÉ B.I.; FRYDMAN, JAIME BENJAMÍN

TETRAHEDRON

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1995 vol. 51 p. 2255 - 2266

0040-4020

The synthesis of two hexacyclic and one heptacyclic biliverdin with extended conformationswas achieved using base catalyzed intramolecular substitution reactions of 2-chloroethyi biliverdins. The 2-chloroethyl residues were located at selected 13-pyrrole positions as to enable them to react with proximal basic nitrogens at the adjacent pyrrole rings. Seven membered rings were thus formed which distorted either two or the three exocyclic double bonds at the biliverdin meso-bridges away from their usual Z-syn configuration. The hexacyclic biliverdin 9 is isomorphous with the chromophores of Cphycocyanin, biliverdin 19 is an isomer of isophorcabilin, and the heptacyclic biliverdin 34 has the fullest extended conformation that the biliverdin backbone can achieve.