1: 86 percent / pyridine, N,N-dimethyl-4-aminopyridine (DMAP) / CH2Cl2 / 4 h / Ambient temperature 2: 42 percent / 22 h / 0.1 M phosphate buffer (pH 7.0), Pseudomonas sp. (SAM II) lipase 3: 1.) trimethyloxonium tetrafluoroborate, 2.) aq. NaOH / 1.) CH2Cl2, RT, 2 h, 2.) CH2Cl2, 2.5 h View Scheme

1: 86 percent / pyridine, N,N-dimethyl-4-aminopyridine (DMAP) / CH2Cl2 / 4 h / Ambient temperature 3: 99 percent / K2CO3, H2O / methanol / 12 h / Ambient temperature 4: 1.) trimethyloxonium tetrafluoroborate, 2.) aq. NaOH / 1.) CH2Cl2, RT, 2 h, 2.) CH2Cl2, 2.5 h View Scheme