↑Reilly, J.; Hickinbottom, W. J. J. Chem.Soc. 1920, 103-137
↑Thermal and Acid-Catalyzed Hofmann-Martius Rearrangement of 3-N-Aryl-2-oxindoles into 3-(Arylamino)-2-oxindoles Philip Magnus and Rachel Turnbull Org. Lett.; 2006; 8(16) pp 3497 - 3499; (Letter) doi:10.1021/ol061191z
↑heating 1 in toluene at 80°C gives 30% 2-o (ortho) and 37% 2-p (para)