Dipolar Cycloadditions to Polypyrrolic Macrocycles

MacAlpine etal, US Patent 6,620,929 (September 16, 2003) Assignee University of British Columbia 

Utility Therapeutic Photosensitizing Agents in the Treatment of Tumors 

A solution of 5,10,15,20-tetraphenylporphyrin (0.08 mmol) and tetracyanoethylene oxide (0.34 mmol) dissolved in 2 ml 1,2-dibromoethane were refluxed 1 hour. The solvent was evaporated in vacuo and the product isolated by chromatography on silica using hexane/chloroform, 1 1. H-NMR, UV-Vis, MS, and elemental analysis data supplied. 

A review of nucleophilic reactions involving tetracyanoethylene is provided (3). 

When 5,15-diphenylporphyrin was refluxed 3 hours in toluene with tetracyanoethylene oxide, two compounds were formed by a /3-addition as illustrated in Eq. 1. In a subsequent investigation by the author (4), however, it was discovered that if the mixture was refluxed 24 hours, only the tetracyano derivative would be obtained. 

---