in dichloromethane under nitrogen, 41°C, 48 h,; TLC monitoring, solvent removed (vac.); residue washed (warm petroleum ether, chromy. (silica, CH2Cl2/petroleum ether 2/1, v/v), crystn. from eluant solvent, elem. anal.;

in dichloromethane under nitrogen, 41°C, 24 h, some decompn. obsd.; TLC monitoring, solvent removed (vac.); residue washed (warm petroleum ether; chromy. (silica, CH2Cl2/petroleum ether 2/1, v/v), crystn. from eluant solvent, elem. anal.;