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1.1 INTRODUCTION
Though Bayer 1 determined its constitution in 1900, Runge 2 was first to
discovered pyrrole in 1834 as a certain coal tar fraction which was presumably
responsible for this by hydrochloric acid of pine shaving previously dipped in
them.
Anderson 3 characterized the structure of pyrrole in 1857 and was later
synthesized by heating the ammonium salt of music acid.
Pyrrole is an important π-electron excessive aromatic heterocycle. This ring
system is incorporated as a basic structural unit in several natural pigment
porphyrins, porphin (heme), chlorine (chlorophyll), and corrins (vitamin B 12 ).
Moreover the presence of pyrrole ring in porphobolinogen (I) (intermediate in
biosynthesis of porphyrins and vitamin B 12 ) has provided an impetus to the
pyrrole chemistry.
O
O
OH
HO
H 2 N
N
H
(I)
Many alkaloids and amino acids namely, proline and hydroxyl proline also contain
the reduce pyrrole system (pyrrolidine) 4 . Many natural products containing pyrrole
ring are also known 5-8 .
C H 3
N
H
O
O
CH 3
N
CH 3
O
HO
(II) (III) (IV)
H
O
CH 3
CH 3
HO
O
O
CH 3
Cl
O -
N +
O
Cl
N
H
(V)
N
H
(VI)