1.1: 91 percent / p-acetamidobenzenesulfonyl azide; Et3N / acetonitrile / 3 h / 20 °C 2.1: 96 percent / Et3N / CH2Cl2 / 1 h / 0 °C 3.1: [Rh2{(S)-N-phthaloyl-tert-leucinate}4] / toluene / 1 h / -78 °C 4.1: O3 / methanol / -78 °C 4.2: H2O2; formic acid / methanol / 30 h / Heating View Scheme

1.1: 91 percent / p-acetamidobenzenesulfonyl azide; Et3N / acetonitrile / 3 h / 20 °C 2.1: 96 percent / Et3N / CH2Cl2 / 1 h / 0 °C 3.1: [Rh2{(S)-N-phthaloyl-tert-leucinate}4] / toluene / 1 h / -78 °C 4.1: O3 / methanol / -78 °C 4.2: H2O2; formic acid / methanol / 30 h / Heating 5.1: p-toluenesulfonic acid / methanol View Scheme