Synthesis
General procedure for the synthesis of 2-chloro-1,10-phenanthroline from 1,10-phenanthroline 1-oxide: the procedure was similar to General Procedure I, with the difference that the reaction conditions were adjusted to be carried out at room temperature using 1,10-phenanthroline 1-oxide (1.00 eq.), POBr3 (3.00 eq.), and DMF (1.50 eq.) at a concentration of 0.2M. General procedure I (0013) for the bromination of acridazine N-oxide was carried out as follows: an appropriate amount of acridazine N-oxide was dissolved in anhydrous CH2Cl2 (0.1 M) at 0 °C, POBr3 (1.2 eq.) was added with stirring, followed by a slow, dropwise addition of DMF (0.5 eq.) under argon gas protection. The reaction mixture was gradually warmed to 25 °C with continuous stirring until TLC showed completion of the reaction. Upon completion of the reaction, the pH was adjusted to 7-8 by slow addition of saturated aqueous sodium carbonate solution. the mixture was separated and the aqueous phase was fully extracted with CH2Cl2. All organic phases were combined, washed with brine, dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure to obtain the crude product. The crude product was purified by fast column chromatography with PE/EA (100:1) as eluent.
References
[1] Tetrahedron, 2016, vol. 72, # 38, p. 5762 - 5768
[2] Journal of Organic Chemistry, 2007, vol. 72, # 7, p. 2318 - 2328
[3] Chemistry - A European Journal, 2017, vol. 23, # 27, p. 6499 - 6503
[4] Journal of Organic Chemistry, 2017, vol. 82, # 8, p. 4203 - 4215
