tert.-butyl lithium hexane, THF, 1.) -78 deg C, 30 min, 2.) -40 deg C, 30 min, 1 h, 3.) -78 deg C, 15 min; Yield given. Multistep reaction;

(R)(S)-1-bromo-1,2-butadiene; lithium; ethylene dibromide 1.) ether, -5 deg C, 2 h, 2.) THF, -78 deg C, 15 min; Yield given. Multistep reaction;

(i) MeSOCl, Et3N, (ii) /BRN= 1098267/, LiCuBr2; Multistep reaction;