1: dibromo-difluoro-methane With N,N,N',N',N'',N''-hexamethylphosphoric triamide in tetrahydrofuran T=-78 - 20°C; 2: (+/-)-4,4,6-trimethyl-7-oxabicyclo[4.1.0]heptan-2-one in tetrahydrofuran T=20°C; 1 h;

N,N,N',N',N'',N''-hexamethylphosphoric triamide

1.1: 87 percent / aq. H2O2; NaOH / methanol / 5 h / 0 - 20 °C 2.1: hexamethylphosphorus triamide / tetrahydrofuran / -78 - 20 °C 2.2: 75 percent / tetrahydrofuran / 1 h / 20 °C View Scheme