in toluene (N2); TLC (SiO2), recrystn. (CH2Cl2/hexane);

in toluene (inert atmosphere); stirring (45°C, ca. 12 h); solvent removal under an N2 stream, redissoln. (CH2Cl2), TLC (SiO2; CH2Cl2/hexane), recrystn. (CH2Cl2/hexane); elem. anal.;

in toluene (N2); heating to 45°C; TLC (SiO2), recrystn. (CH2Cl2/hexane);