hexamethylphosphorous triamide dichloride; ammonia in dichloromethane 1) 30 min, -20 deg C, 2) 4 h, r.t.;

1: 90 percent / triethylamine / CH2Cl2 / 3 h 2: 86 percent / 2,4-bis(4-phenoxyphenyl)-1,3-dithia-2,4-diphosphetane 2,4-disulfide (PTPS) / tetrahydrofuran / 6 h / Ambient temperature View Scheme

triethylamine in dichloromethane 3 h;

1.1: 91 percent / BOP; ZnCl2; i-Pr2NEt / acetonitrile / 16 h 2.1: N2H4 / ethanol / 2 h / Heating 2.2: 98 percent / aq. AcOH / 1 h / 100 °C View Scheme