1: (2R,5S)-5-isopropyl-3,6-dimethoxy-2-(nona-1,2-dien-3-yl)-2,5-dihydropyrazine With water; trifluoroacetic acid in tetrahydrofuran T=20°C; 2: di-tert-butyl dicarbonate With triethylamine in dichloromethane T=20°C; 12 h; optical yield given as percent ee;