Tributyltin azide → 3-Tetrazolyl-2-(1,1-dimethylethoxy)methanamidopropionic acid

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Reaction Steps

17.5 g (82 mmol, 1 equiv.) of the compound of Example 39 (3-cyano-2-(1,1-dimethylethoxy)methanamide-propionic acid) was dissolved in 125 mL of THF and 40.5 g (129 mmol, 1.5 equiv.) tributyltin azide was added. The reaction mixture was brought to reflux and held there for 3 days. The reaction mixture was cooled and the volatile removed in vacuo on the rotary evaporator. The residue was dissolved in 300 mL of 0.5M NaOH and this aqueous solution was washed with ethyl acetate (4×100 mL). The aqueous layer was passed through a 125 mL bed of Dowex 50X8-400 ion exchange resin and the resin washed with four column volumes of 1:1 methanol:water. The volatiles were removed in vacuo on the rotary evaporator to yield 17.9 g of the title compound as a white solid (85% yield). 1H-NMR (CD3OD): 4.55 p.p.m. (m, 1H); 3.40 p.p.m. (m, 2 H); 1.40 p.p.m. (s, 9H). This material is suitable for use in solid-phase peptide synthesis.

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