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2. α-amino ketones react with alkynes, undergoes nucleophilic-electrophilic
interaction to provide pyrrole 18 .
3
H 3 C O
R
CH 3
+
O
O
O
CH 3
C H 3
(CH 3
) 3
CO - K + R N
CH H
3
O
O
O
O
CH 3
CH3
O
R=H, CH 3
, C 2
H 5
3. Piloty- Robinson Pyrrole synthesis 19
The condensation of aliphatic aldehyde or ketones with hydrazine under strongly
acidic conditions affords pyrrole. This reaction can also be applied for the
preparation of N-substituted pyrroles by condensing ketones with methyl
hydrazine or N,N-Dimethyle hydrazine.
CH 3
CH 3
H 3 C
CH 3
N
N
CH 3
CH 3
HCl
H3C
N
H
+ NH 3
H 3 C
4. Hantsch Pyrrole synthesis 20
The reaction of β- keto or β- keto esters with α-halo ketones or aldehyde in the
presence of ammonia or primary amine affords pyrroles.
Cl
+
H 3 C
O
O
O
O CH 3
H 3
O CH 3
NH 3
N
C
H
O
CH 3
CH 3