1: N1'-DMTr-biotin methylester With sodium hydride in N,N-dimethyl-formamide; mineral oil 0.5 h; Inert atmosphereCooling with ice; 2: undec-10-enoic acid chloride With tetra-(n-butyl)ammonium iodide in N,N-dimethyl-formamide; mineral oil T=20°C; Cooling with iceInert atmosphere; regioselective reaction;

1: N1'-DMTr-biotin methylester With sodium hydride in N,N-dimethyl-formamide; mineral oil 0.5 h; Inert atmosphereCooling with ice; 2: p-toluenesulfonyl chloride With tetra-(n-butyl)ammonium iodide in N,N-dimethyl-formamide; mineral oil T=20°C; Cooling with iceInert atmosphere; regioselective reaction;

1: N1'-DMTr-biotin methylester With sodium hydride in N,N-dimethyl-formamide; mineral oil 0.5 h; Inert atmosphereCooling with ice; 2: chloroacetyl chloride With tetra-(n-butyl)ammonium iodide in N,N-dimethyl-formamide; mineral oil T=20°C; Cooling with iceInert atmosphere; regioselective reaction;