1: With N-bromosuccinmide in dichloromethane T=0°C; 2 h; Inert atmosphereDarkness; 2: With 1,8-diazabicyclo[5.4.0]undec-7-ene in dichloromethane T=0 - 20°C; Inert atmosphereDarkness; optical yield given as percent destereoselective reaction;