Synthesis 2008(1): 155-160  
DOI: 10.1055/s-2007-983895
© Georg Thieme Verlag Stuttgart · New York

One-Pot Synthesis of Dihydroimidazo- and Imidazophenanthridinium Salts

Alexis D. C. Parenty*, Leroy Cronin*
WestCHEM, University of Glasgow, Chemistry Department, Glasgow, G12 8QQ, UK
Fax: +44(141)3304888; e-Mail: [email protected]; e-Mail: [email protected];
Further Information

Publication History

Received 15 February 2007
Publication Date:
11 September 2007 (online)


Two highly efficient and general one-pot annulation reactions are described for the synthesis of dihydroimidazo- and imidazophenanthridinium salts (DIPs + and IPs +). These two methodologies exploit the difference in reactivity between primary amino-based or ammonia nucleophiles and the dielectrophilic starting material, 2-bromoethylphenanthridinium bromide.


  • 1 Brana MF. Cacho M. Gradillas A. de Pascual-Teresa B. Ramos A. Curr. Pharm. Des.  2001,  7:  1745 
  • 2a Morohashi K. Yoshino A. Yoshimori A. Saito S. Tanuma S. Sakaguchi K. Sugawara F. Biochem. Pharmacol.  2005,  70:  37 
  • 2b Boibessot I. Tettey JNA. Skellern GG. Watson DG. Grant MH. J. Vet. Pharmacol. Ther.  2006,  29:  547 
  • 2c Harayama T. Akiyama T. Nakano Y. Shibaike K. Akamatsu H. Hori A. Abe H. Takeuchi Y. Synthesis  2002,  237 
  • 3a Whittaker J. McFadyen WD. Baguley BC. Murray V. Anti-Cancer Drug Des.  2001,  16:  81 
  • 3b Whittacher J. McFadyen WD. Wickham G. Wakelin LPG. Murray V. Nucleic Acids Res.  1998,  26:  3933 
  • 4 Ihmels H. Otto D. Top. Curr. Chem.  2005,  258:  161 
  • 5a Pennadam SS. Ellis JS. Lavigne MD. Górecki DC. Davies MC. Alexander C. Langmuir  2007,  23:  41 
  • 5b Sammes PG. Shek L. Watmore D. Chem. Commun.  2000,  1625 
  • 6 Parenty ADC. Smith LV. Pickering AL. Long DL. Cronin L. J. Org. Chem.  2004,  69:  5934 
  • 7 Parenty ADC. Guthrie KM. Song YF. Smith LV. Burkholder E. Cronin L. Chem. Commun.  2006,  1194 
  • 9 Parenty ADC. Smith LV. Guthrie KM. Long DL. Plumb J. Brown R. Cronin L. J. Med. Chem.  2005,  4504 
  • 10a Guthrie KM. Parenty ADC. Smith LV. Cronin L. Cooper A. Biophys. Chem  2007,  126:  117 
  • 10b Smith LV. Parenty ADC. Guthrie KM. Plumb J. Brown R. Cronin L. ChemBioChem  2006,  7:  1757 
  • 10c Smith LV. De la Fuente JM. Guthrie KM. Parenty ADC. Cronin L. New J. Chem.  2005,  29:  1118 
  • 11 Parenty ADC. Smith LV. Cronin L. Tetrahedron  2005,  61:  8410 
  • 12 Kearney AM. Vanderwal CD. Angew. Chem. Int. Ed.  2006,  45:  7803 
  • 13 Parenty ADC. Song YF. Richmond C. Cronin L. Org. Lett.  2007,  9:  2253 

Due to resonance electron donation, the amidinium moiety of DIP +s and IP +s makes the positive charge more stable than the one on the iminium moiety of ordinary phenanthridinium derivatives and therefore confers better resistance to the common nucleophilic attack of hydroxide at physiological pH.


The quantity of electrophilic reactant added in excess depends on its physical properties: 20 equivalents were used with low boiling point inexpensive material, whereas only 2 equivalents were necessary with solid starting material.


With the exception of the electrophile HBr, where r.t. conditions and only 1 min stirring were used on 1 mL of a 48% HBr aqueous solution.