1: C13H23NO3 With 2,6-dimethylpyridine; oxalyl dichloride in toluene T=0°C; 1 h; 2: 1-(2'-(1-trityl-1H-tetrazol-5-yl)biphenyl-4-yl)methanamine in toluene T=0 - 20°C; 1 h;