boron trifluoride diethyl etherate; hydrazine hydrate 1.) CHCl3, reflux, 20 h; 2.) EtOH, 60 deg C, 15 min; Yield given. Multistep reaction. Yields of byproduct given;

tin(IV) chloride in chloroform 0.5 h; Ambient temperaturevar. Lewis acids, other temp., var. times;

in chloroform 12 h; Ambient temperature;