1: 82 percent / pyridine / 72 h / 0 °C 2: 82 percent / lithium aluminium hydride / tetrahydrofuran / 1.) -10 deg C 2.) RT View Scheme

1: PBr3 / diethyl ether 2: (i) collidine, (ii) aq. HCl, (iii) O3, AcOEt View Scheme