Trifluoroacetic acid → Sodium 3,6-disulfonaphthylthiourea

Beteiligte Stoffe

Reaktionsschritte

Trifluoroacetic acid (2 ml) was added to a suspension of BHAlyslys2lys4lys8DBL16 (73 mg; 0.01 mmol) in dry dichloromethane (2 ml) under nitrogen A vigorous evolution of gas was observed for a short time and the resulting solution was stirred at room temperature for two hours and then concentrated. The residual syrup was dissolved in water (5 ml), the solution passed through a column of Amberlite IRA-401 (OH) and the filtrate concentrated to give BHAlyslys2lys4lys8lys16 as a viscous oil. The oil was redissolved in water (5 ml) and N,N-dimethyl-N-allylamine buffer (pH 9.5; 3 ml) added. Solid sodium 3,6-disulfonapthylisothiocyanate (234 mg; 0.60 mmol) was then added and the resulting solution heated under nitrogen at 53° for two hours and then cooled. The solution was concentrated and the brownish solid residue purified by gel filtration (Sephadex LH20; water). The pure fractions were combined, passed through a column of Amberlite IR 120(Na) and freeze dried to give BHAlyslys2lys4lys8lys16 terminated with 32 sodium 3,6-disulfonapthylthiourea groups as a fluffy off-white solid (119 mg). 1H nmr (D2O): δ 1.0-2.0; 3.18; 3.43; 4.31; 7.22; 7.80; 7.89; 8.25. 13C nmr (D2O): δ 27.2; 32.4; 35.3; 43.7; 49.0; 58.5; 63.6; 128.4; 129.1; 131.4; 136.1; 136.6; 138.6; 139.0; 145.1; 145.6; 178.4; 184.8; 186.7.

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