Synthesis and Crystal Structures of 4-(3-Nitropyridin-2-ylamino)phenol and 4-(3-Aminopyridin-2-ylamino)phenol

The title compounds, 4-(3-nitropyridin-2-ylamino)phenol (I) and 4-(3-aminopyridin-2-ylamino)phenol (II), are two intermediates for the synthesis of a potential antitumor agent ABT-751. The reaction of 4-aminophenol with 2-chloro-3-nitropyridine yielded I which was converted into II by reduction. Instead of the Pd/C catalytic hydrogenation described in many literature, reduction with cheap sodium sulfide in aqueous media was utilized for shorting the reaction time and simplifying the operation. The crystal structures of the resultant compounds were determined by single-crystal X-ray diffraction. The compound I is crystallized in P2(1)/c space group of monoclinic system, with a = 11.5236(19) , b = 8.7389(17) , c = 10.684(3) and alpha = 90.00A degrees, beta A = 107.76(3)A degrees, gamma A = 90.00A degrees. The compound II is crystallized in Cc space group of monoclinic system, with a = 10.688(2) , b = 14.2181(18) , c = 7.9836(15) and alpha = 90.00A degrees, beta A = 125.801(7)A degrees, gamma A = 90.00A degrees. In both crystal structures, the intermolecular N-H-O and O-H-N hydrogen bonds link the molecules, which effectively stabilize the structures.