1: (2-oxoheptyl)phosphonic acid dimethyl ester With lithium hydroxide in tert-butyl methyl ether T=20°C; 1 h; 2: (3aR,4R,5R,6aS)-5-(benzoyloxy)hexahydro-2H-cyclopenta[b]furan-2-one-4-carboxaldehyde in tert-butyl methyl ether; water T=20°C; 1 h;

sodium hexamethyldisilazane in tetrahydrofuran T=-78 - 20°C; Inert atmosphere;

1: dimethyl (2-oxoheptyl)phosphonate With sodium hydride in tetrahydrofuran T=0 - 20°C; 2: (3aR,4R,5R,6aS)-5-(benzoyloxy)hexahydro-2H-cyclopenta[b]furan-2-one-4-carboxaldehyde in tetrahydrofuran T=20°C; 1.5 h;

sodium hexamethyldisilazane in tetrahydrofuran T=-78 - 20°C; Horner-Emmons reaction;

lithium hexamethyldisilazane in tetrahydrofuran T=-78 - 20°C; Horner-Emmons reaction;

1: 80 percent / (S)-BINAL-H; EtOH / tetrahydrofuran / 1 h / -100 °C 2: 95 percent / DMAP; imidazole / CH2Cl2 / 4.5 h / 20 °C View Scheme