hydrogen bromide in diethyl ether 1.) from -70 deg C to room temperature, 2.) room temperature, 1 h;

bromine; mercury(II) oxide in dichloromethane Heating;

bromine beim Ausschluss von Licht;

(i) TsCl, Py, (ii) NaBHEt3, Et2O; Multistep reaction;

1: 1-bromo-1-methylcyclopropane With tert.-butyl lithium in diethyl ether; pentane T=-70 - -30°C; 1 h; Cooling with acetone-dry ice; 2: cyclopent-2-enone in diethyl ether; pentane T=-70°C; 1 h; 3: With palladium on activated charcoal; hydrogen