3-(3-Pyrrolyl)thiopyrrolidones as precursors of benzo[1,2-b:4,3-b']dipyrroles. Synthesis of structures related to the phosphodiesterase inhibitors PDE-I and PDE-II
3-(3-Pyrrolyl)thiopyrrolidones as precursors of benzo[1,2-b:4,3-b']dipyrroles. Synthesis of structures related to the phosphodiesterase inhibitors PDE-I and PDE-II