1: Thiolactone With lithium hexamethyldisilazane in tetrahydrofuran T=0°C; 0.5 h; 2: n-octyl halide in tetrahydrofuran T=0 - 20°C;

sodium hexamethyldisilazane in tetrahydrofuran T=-78 - -5°C; Dieckmann condensation;

1: Thiolactone With N,N'-dimethyl-N,N'-propyleneurea; sodium hydride in tetrahydrofuran T=20°C; 0.5 h; 2: With n-butyllithium in tetrahydrofuran; hexane T=-78 - 20°C; 3: 1-iodo-n-octane in tetrahydrofuran; hexane T=-78 - 20°C;

1.1: LiHMDS / tetrahydrofuran / -78 °C 1.2: 81 percent / tetrahydrofuran / -78 °C 2.1: ethanol / 2 h / 20 °C 3.1: 484 mg / NEt3 / CH2Cl2 / 0.67 h / 0 °C 4.1: 70 percent / NaHMDS / tetrahydrofuran / -78 - -5 °C View Scheme

1: 484 mg / NEt3 / CH2Cl2 / 0.67 h / 0 °C 2: 70 percent / NaHMDS / tetrahydrofuran / -78 - -5 °C View Scheme

1.1: pyridinium tribromide; acetic acid / 20 °C 2.1: Et3N / ethyl acetate / 20 °C 3.1: 90 percent / KOH / H2O; ethanol / 3 h / 40 °C 4.1: NaH; 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone / tetrahydrofuran / 0.5 h / 20 °C 4.2: BuLi / tetrahydrofuran; hexane / -78 - 20 °C 4.3: 12 percent / tetrahydrofuran; hexane / -78 - 20 °C View Scheme

1.1: 90 percent / KOH / H2O; ethanol / 3 h / 40 °C 2.1: NaH; 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone / tetrahydrofuran / 0.5 h / 20 °C 2.2: BuLi / tetrahydrofuran; hexane / -78 - 20 °C 2.3: 12 percent / tetrahydrofuran; hexane / -78 - 20 °C View Scheme

1.1: Et3N / ethyl acetate / 20 °C 2.1: 90 percent / KOH / H2O; ethanol / 3 h / 40 °C 3.1: NaH; 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone / tetrahydrofuran / 0.5 h / 20 °C 3.2: BuLi / tetrahydrofuran; hexane / -78 - 20 °C 3.3: 12 percent / tetrahydrofuran; hexane / -78 - 20 °C View Scheme