1: triphenylbenzyl-phosphonium bromide in tetrahydrofuran; hexane T=-78°C; 1 h; Inert atmosphere; 2: C13H10N2O4S in tetrahydrofuran; hexane T=-78 - 20°C; 12 h; Inert atmosphere;

in acetonitrile T=25°C; 24 h; Inert atmosphere; optical yield given as percent destereoselective reaction;

in dichloromethane T=25°C; 12 h; Inert atmosphere; optical yield given as percent destereoselective reaction;