1.1: hexamethyldisilazane; n-BuLi / tetrahydrofuran; hexane / -78 - -30 °C 1.2: 82 percent / tetrahydrofuran; hexane / 70 h / -78 - 20 °C 2.1: 66 percent / aq. NaOH / propan-2-ol / 16 h / 45 °C 3.1: 89 percent / TBAF / tetrahydrofuran / 16 h / 0 - 25 °C 4.1: 1,3,5-Cl3C6H2COCl; Et3N / tetrahydrofuran / 0.75 h / 0 °C 4.2: 63 percent / DMAP / toluene; tetrahydrofuran / 4.5 h / 75 °C 5.1: 83 percent / TFA / CH2Cl2 / 4.5 h / 0 °C 6.1: 52 percent / KO2CN=NCO2K; AcOH / CH2Cl2 / 25 h / Heating 7.1: 78 percent / dimethyldioxirane / CH2Cl2 / -50 °C View Scheme

1.1: hexamethyldisilazane; n-BuLi / tetrahydrofuran; hexane / -78 - -30 °C 1.2: 82 percent / tetrahydrofuran; hexane / 70 h / -78 - 20 °C 2.1: 66 percent / aq. NaOH / propan-2-ol / 16 h / 45 °C 3.1: 89 percent / TBAF / tetrahydrofuran / 16 h / 0 - 25 °C 4.1: 1,3,5-Cl3C6H2COCl; Et3N / tetrahydrofuran / 0.75 h / 0 °C 4.2: 63 percent / DMAP / toluene; tetrahydrofuran / 4.5 h / 75 °C 5.1: 83 percent / TFA / CH2Cl2 / 4.5 h / 0 °C 6.1: 52 percent / KO2CN=NCO2K; AcOH / CH2Cl2 / 25 h / Heating View Scheme