Diisopropylethylamine → N-tert-butoxycarbonyl O-allyl L-seryl glycine methyl ester

Participants

Reaction Conditions

Reaction Steps

Purified N-tert-butoxycarbonyl O-allyl L-serine 3 (6.94 g, 28.3 mmol) was dissolved in 30 mL DMF and the solution cooled to 0° C. (icebath). Glycine methyl ester hydrochloride (3.55 g, 28.3 mmol) was suspended in 10 mL DMF and N,N-diisopropylethyl amine (3.66 g, 28.3 mmol) added. The suspension was then added in one portion to the solution of 3 together with an additional 5 mL DMF. HOBt hydrate (4.33 g, 28.3 mmol) was added. Finally, EDC hydrochloride (5.97 g, 31.1 mmol) was added together with an additional 10 mL DMF. The reaction mixture was stirred at 0° C. for 1 hour. In total the reaction mixture was stirred for 24 hours before the solvent was evaporated. The residue was taken up in 150 mL EtOAc and washed with 1 M aqueous H2SO4 (3×100 mL), 7.5% (w/w) aqueous K2CO3 (3×100 mL) and finally saturated brine (100 mL). The solution was dried with anhydrous MgSO4 and the solvent evaporated affording a clear and slightly greenish/yellowish liquid (7.49 g, 84%); δH (200 MHz; d6-DMSO) 8.31 (1H, t, J 6, NH(Gly)), 6.85 (1H, d, J 8, NH(Ser(All))), 5.86 (1H, ddt, J 5, 11 and 17, CH═CH2), 5.29-5.11 (2H, m, CH═CH2), 4.22 (1H, ddd, J 8 and 12, CαH(Ser(All))), 3.94 (2H, dt, J 1 and 5, CH2CH═CH2), 3.86 (1H, d, J 6, CαHH(Gly)), 3.83 (1H, d, J 6, CαHH(Gly)), 3.62 (3H, s, OCH3), 3.56-3.44 (2H, m, CH2), 1.38 (9H, s, (CH3)3); δC (50 MHz; d6-DMSO) 170.3, 170.0, 155.1, 134.9, 116.3, 78.2, 70.9, 69.6, 54.1, 51.6, 40.5, 28.1; m/z (ESI) 339.1541 ([M+Na]+; C14H24N2O6Na requires 339.1532)

Provenance & Evidence