H. C. Guo, R. Zheng, H. J. Jiang
Jan 1, 2012
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0
Influential Citations
16
Citations
Journal
Organic Preparations and Procedures International
Abstract
1,10-Phenanthroline is a classic ligand that plays an important role in coordination chemistry and continues to be of considerable interest as a versatile starting material in organic, inorganic and supramolecular chemistry.1,2 As for 1,10-phenanthroline derivatives, most of the recent work has been prompted by the intense current interest in their molecular recognition, photophysical, catalysis, redox properties and cleavages of DNA.3–5 Thus, a simple and convenient access to 1,10-phenanthroline building blocks appears of importance. Surprisingly, the functionalization of the 2,9-positions of 1,10-phenanthroline ligand appears to be relatively rare. Among these derivatives, 2,9-dihalo-1,10-phenanthrolines are the most versatile starting materials of particular importance as they can be used either directly for metal-catalyzed cross-coupling reactions to form additional derivatives or for the preparation of the 2,9-diamino,6 2,9-dialkoxy7 and 2,9-diacetyl8 analogues. The synthesis of 2,9-dichloro-1,10-phenanthroline (4) has been reported by two groups. The conventional method (Route 1, Scheme 1) leads to 4 in six steps and in low overall yields (44%) from 1,10-phenanthroline (1).9,10 Compound 4 has also been obtained in a three-step sequence (Route 2, Scheme 2) from 1.11,12 Compound 2 was obtained in 88% yield by