1: With phosphoric acid trimethyl ester; N,N,N',N'-tetra-methylnaphthalene-1,8-diamine; trichlorophosphate T=0 - 4°C; 2: With (HNBu3)2P2O7 in N,N-dimethyl-formamide T=0°C; 3: With triethylammonium hydrogen bicarbonate buffer in N,N-dimethyl-formamide T=20°C; pH=7.4 - 7.6; 1 h;

1.1: 93 percent / NaOCH3 / methanol / 3 h / 20 °C 2.1: (OCH3)3PO; POCl3; 1,8-bis(dimethylamino)naphthalene / 0 - 4 °C 2.2: bis(tri-n-butylammonium)pyrophosphate / dimethylformamide / 0 °C 2.3: aq. triethylammonium hydrogen bicarbonate buffer / dimethylformamide / 1 h / 20 °C / pH 7.4 - 7.6 View Scheme