Yield:-

Steps:

Multi-step reaction with 2 steps
1: 72 percent / hydroxylamine hydrochloride; sodium sulfate; aq. HCl / 55 °C
2: conc. sulfuric acid / 55 - 80 °C

References:

Kaila, Neelu;Janz, Kristin;DeBernardo, Silvano;Bedard, Patricia W.;Camphausen, Raymond T.;Tam, Steve;Tsao, Desirée H.H.;Keith Jr., James C.;Nickerson-Nutter, Cheryl;Shilling, Adam;Young-Sciame, Ruth;Wang, Qin [Journal of Medicinal Chemistry,2007,vol. 50,# 1,p. 21 - 39]