titanium tetrachloride in dichloromethane T=0 - 25°C; 5.5 h;

trichlorophosphate in toluene T=30 - 80°C; Vilsmeier reaction; 2 h;

hydrogenchloride; formaldehyd; 4-hydroxyl-amino-toluene-sulfonic acid-(2)

1: 2.) aq. NaOH / 1) 180 deg C, 5 h; 2) reflux, 1.5 h 2: 1.) butyllithium / 1) diethyl ether, hexane, -15 to -10 deg C, 25 min, -10 deg C, 10 min, rt, 45 min; 2) diethyl ether, hexane, rt, 30 min View Scheme

n-butyllithium 1) diethyl ether, hexane, -15 to -10 deg C, 25 min, -10 deg C, 10 min, rt, 45 min; 2) diethyl ether, hexane, rt, 30 min; Yield given. Multistep reaction;