1.1: oxalyl chloride / CH2Cl2 / 2 h / Heating 2.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 2.2: 43 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 3.1: n-BuLi / tetrahydrofuran; hexane / 1 h / 0 °C 3.2: 84 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 4.1: O3 / methanol / 0.5 h / -10 °C 4.2: 60 percent / thiourea / methanol / 0.92 h / 0 °C 5.1: H2 / 10 percent Pd/C / methanol / 1 h 5.2: 96 percent / diethyl ether / 20 °C 6.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 1.2: 43 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 2.1: n-BuLi / tetrahydrofuran; hexane / 1 h / 0 °C 2.2: 84 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 3.1: O3 / methanol / 0.5 h / -10 °C 3.2: 60 percent / thiourea / methanol / 0.92 h / 0 °C 4.1: H2 / 10 percent Pd/C / methanol / 1 h 4.2: 96 percent / diethyl ether / 20 °C 5.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1.1: H2 / 10 percent Pd/C / methanol / 1 h 1.2: 96 percent / diethyl ether / 20 °C 2.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1.1: O3 / methanol / 0.5 h / -10 °C 1.2: 60 percent / thiourea / methanol / 0.92 h / 0 °C 2.1: H2 / 10 percent Pd/C / methanol / 1 h 2.2: 96 percent / diethyl ether / 20 °C 3.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 1 h / 0 °C 1.2: 84 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 2.1: O3 / methanol / 0.5 h / -10 °C 2.2: 60 percent / thiourea / methanol / 0.92 h / 0 °C 3.1: H2 / 10 percent Pd/C / methanol / 1 h 3.2: 96 percent / diethyl ether / 20 °C 4.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1.1: LDA / tetrahydrofuran; hexane / 0.67 h / 0 °C 1.2: 84 percent / tetrahydrofuran; hexane / 3 h 2.1: oxalyl chloride / CH2Cl2 / 2 h / Heating 3.1: n-BuLi / tetrahydrofuran; hexane / 0.5 h / -78 °C 3.2: 43 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 4.1: n-BuLi / tetrahydrofuran; hexane / 1 h / 0 °C 4.2: 84 percent / tetrahydrofuran; hexane / 0.5 h / -78 °C 5.1: O3 / methanol / 0.5 h / -10 °C 5.2: 60 percent / thiourea / methanol / 0.92 h / 0 °C 6.1: H2 / 10 percent Pd/C / methanol / 1 h 6.2: 96 percent / diethyl ether / 20 °C 7.1: 72 percent / aq. sodium chlorite; sodium dihydrogen phosphate; 2-methyl-2-butene / 2-methyl-propan-2-ol / 0.5 h / 20 °C View Scheme

1: in tetrahydrofuran; diethyl ether T=-78°C; 3 h; 2: With lithium hydroxide; dihydrogen peroxide in tetrahydrofuran; water T=0°C; 7 h; Title compound not separated from byproducts;

sodium hydroxide in methanol

2: 1M NaOH / methanol View Scheme

1: 90 percent / H2O2; aq. LiOH / tetrahydrofuran / 1 h / 0 °C 2: 100 percent / CF3COOH / CH2Cl2 / 12 h View Scheme