To a 250 ml round bottom flash, charged with 10.0 g (0.041 mole) of N ε-(tert-butoxy carbonyl) L-lysine 27, commercially available from BACHEM Bioscience Inc. (subsidiary of BACHEM Switzerland, 3700 Horizon Drive, Renaissance at Gulph Mills, King of Prussia, Pa., 19406, USA), and 100 ml of methanol is added 10.0 g (0.07 mole) of ethyl trifluoroacetate followed by 20.0 ml (0.144 mole) of triethylamine. The mixture is stirred at 20-30° C. for 20 hours and then concentrated via rotary evaporation. The residue is diluted with 50 ml of diethyl ether and then filtered. The filtrate is then washed with 3×30 ml aliquots of 1N aqueous HCL, 20ml of deionized water, and finally with 20 ml of deionized water. The organic phase is dried over anhydrous magnesium sulfate, filtered and concentrated. The residue is distilled under vacuum to yield product 28 in good yield. N ε-(tert-butoxy carbonyl) N1α-trifluoroacetyl L-lysine is reacted with tri-o-acetyl tet-Gal-NAC 1-a-S-Pentylamine in the presence of a BOP reagent. The activated carboxylic acid reacts with the clustered galactosamine in DMF and Triethylamine to afford galactose cluster lysine adduct 29 in good yield. The N α-trifluoroacetyl protection of the lysine is removed to afford Primary α-amino lysine-galactose cluster 29a in moderate yield.
