796
S.S. Ali / Chinese Chemical Letters 22 (2011) 793–796
somewhat greater time as compared to the o/p substituents. Heteroaromatic ketones reacted fast and gave excellent
yields of desired imidazoles. A nearly stoichiometric amount of ammonium acetate was used in the course of the
reaction, where as previously a many-fold excess of ammonium acetate was required. This is an additional advantage
of the novel methodology. The possible mechanism of this reaction is shown in (Scheme 2). The K4[Fe(CN)6]Á3H2O
increase the electrophilic character of aromatic aldehyde towards the ammonia to give the imines as intermediate I.
Further catalyst KFCT condenses with the carbonyl oxygens of the ketone, which on dehydration afford the
intermediate II. Intermediates I and II combine for the formation of intermediate III, which on dehydration and further
cyclisation afford the corresponding desired products (Scheme 2).
In conclusion, the K4[Fe(CN)6]Á3H2O has been employed as a novel, mild, and very efficient catalyst for the
convenient synthesis of 2-phenylimidazo[4,5-f][1,10]phenanthrolines in excellent yields from wide variety of
aldehyde. In addition, low-cost of catalyst, solvent-free conditions, environmental friendliness, easy availability, make
this methodology a valid contribution to the existing processes in the field of 2-phenylimidazo[4,5-f] [1,10]
phenanthrolines derivatives synthesis.
Acknowledgments
We wish to thank Mr. Tilawat Ali the president of Sir Sayyed College for providing necessary facility for research
work.
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