1: ethyl 2-oxo-cyclopentanecarboxylate With potassium carbonate in acetone 0.25 h; 2: n-bromopentane in acetone 6 h; Heating / reflux;

para-dicyanobenzene; phenanthrene in water; acetonitrile 6 h; Inert atmosphereIrradiation;

hydrogenchloride in acetic acid 20 h; Heating;

hydrogenchloride; N-bromosuccinmide; acetic acid 1) CCl4, reflux, 3 h, 2) reflux, 30 h; Yield given. Multistep reaction;

1: 75 percent / aq. HCl / acetic acid / 20 h / Heating 2: sulfuryl chloride / CCl4 / 24 h 3: 76 percent / lithium bromide, lithium carbonate / dimethylformamide / 1 h / Heating 4: diethyl ether / 0.17 h / Ambient temperature 5: 0.5 g / chromium trioxide, sulfuric acid / 0.25 h View Scheme

1: HCl / acetic acid 2: TsOH 3: (i) Br2, CaCO3, (ii) LiBr, Li2CO3 5: aq. NaOH View Scheme

1: HCl / acetic acid 2: TsOH 3: (i) Br2, CaCO3, (ii) LiBr, Li2CO3 4: (i) Li<N(SiMe3)2>, (ii) /BRN= 1857975/ 5: CrO3, H2SO4 View Scheme

1: HCl / acetic acid 2: TsOH 3: (i) Br2, CaCO3, (ii) LiBr, Li2CO3 View Scheme