4-Hydroxymethyl-2'(t-butoxycarbonylaminomethyl)-1,1'-biphenyl (70 mg; 0.224 mmol) was dissolved in dry methylene chloride and stirred at 0° C. in an iced water bath and methanesulfonyl chloride (22 μl; 0.285 mmol) and triethylamine (39 μl; 0.280 mmol) added. The reaction mixture was stirred for 3 h at 0° C. and then 70% aqueous ethylamine (5 ml) added. The mixture was stirred for 5 h at room temperature vigorously, then partitioned between water and methylene chloride. The organic phase was separated and the aqueous layer extracted with methylene chloride (2×25 ml). The combined methylene chloride layers were dried over potassium carbonate powder, filtered and evaporated under reduced pressure to leave a thick viscous oil. The oil was subjected to a short column chromatography using a solvent gradient initially of ethyl acetate and hexanes (1:1 v/v) then neat ethyl acetate and finally with ethyl acetate and methanol (3:1 v/v). This afforded 52 mg (68%) of the desired product. FAB-MS:- calculated for C21H28N2O2 340.2 found 341.1 (M+1).
