Page 35 - Org 3 theoritical book 2024-25
P. 35

Clinical Pharmacy PharmD - 2024/2025                  Level 2                Pharmaceutical Organic Chemistry-3 (PC 305)
            Nucleophilic substitution:


            Generally, the five-membered heterocycles (as -excessive hetero-aromatics) do not

            undergo nucleophilic substitution.

            General methods of preparation:


            Paal-Knorr synthesis:

                    By  heating  1,4-dicarbonyl  compounds  with    various  reagents.  The  choice

            depends on the desired product.












                                                     1- Pyrrole


            Pyrrole  is  a  very  important  five-membered  heterocyclic  as  it  exists  in  many

            natural  products  as  alkaloids,  chlorophyll,  haematin,  vitamin  B 12,  nucleic

            acids...etc.

            Synthesis:

            1) By distillation of succinimide with zinc dust:









            2) By heating furan with ammonia over Al2O3 as catalyst:
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