1.1: 95 percent / DMSO; (COCl)2; Et3N / CH2Cl2 / -78 - 20 °C 2.1: O3 / CH2Cl2; methanol / -78 °C 2.2: 95 percent / Ph3P / methanol / 1 h 3.1: 9M HCl / tetrahydrofuran / 1 h / 20 °C 4.1: 78 percent / HCO2NH4; 3 Angstroem MS; NaCNBH3 / methanol / 24 h / 20 °C 5.1: 80 percent / HCOOH / Pd/C / methanol / 2 h View Scheme