1.1: 4-methyl-morpholine; chloroformic acid ethyl ester / N,N-dimethyl-formamide; dichloromethane / 1.5 h / -15 °C / |Darkness 1.2: 3 h / 20 °C / |Darkness 2.1: oxalyl dichloride; triethylamine; dimethyl sulfoxide / dichloromethane / 0.5 h / -78 - 20 °C / |Inert atmosphere; |Darkness 3.1: acetic acid; sodium tris(acetoxy)borohydride / tetrahydrofuran / 20 °C / |Darkness 4.1: ethanol / 1.5 h / |Reflux; |Darkness 5.1: pH 7.4 / |UV-irradiation View Scheme