Solid phase synthesis of a hydroxypyrrolidine derivative and its use in solid phase peptide synthesis as constrained statine mimic
Pascal Verdié, Gilles Subra,* Pierre Chevallet, Muriel Amblard and Jean Martinez
Supplementary material
Solution synthesis of 1-fluorenylmethyloxycarbonyl-5-benzyl-4,5-dihydro-2-methyl-4-oxo-1H-pyrrole-3-carboxylic acid 7.
Tert-butyl acetoacetate (1.49 ml, 9 mmol; 3 eq.) was added to a sodium hydride tetrahydrofurane solution (216 mg, 9 mmol; 3 eq.) cooled at 0°C. After 10 min, this solution was placed in a water bath warmed at 60°C. A solution of Fmoc-Phe-OH (1.16 g, 3 mmol; 1 eq.), DIEA (1.04 ml, 6 mmol; 2 eq.) and BOP (1.32 g, 3mmol, 1 eq.) in tetrahydrofurane was then added dropwise and the reaction was stirred during 6 h.
After evaporation of the solvent and addition of 200 ml of ethyl acetate, the resulting solution was washed with 1 M aqueous potassium hydrogenosulfate (2 x 50 ml), dried over sodium sulphate and concentrated under reduced pressure. The oily crude was purified by a silica gel chromatography (ethyl acetate/hexane 2/8). 657 mg (43 %) of pure title tert-butyl ester of compound 7 was then obtained as an oil. (RT= 2.27 min, [M+H]+ m/z=510.6)
Tert-butyl ester was removed in a TFA/DCM/H2O solution (1/1/0.05) for one hour. Solution was concentrated in vacuo. The expected compound 7 was solubilized in acetonitrile/water 1/1 solution, freeze-dried, lyophilised. 585 mg (99%) of white powder were obtained : (RT=1.98 min, [M+H]+ m/z=454.0) 1H NMR (DMSO-d6, 300 MHz) δ: 2.15 ppm (s, 3H), 2.70 ppm (m, 2H), 3.95 ppm (br s, 1H), 4.44 (t, 1H, J = 3.5 Hz), 5.01 ppm (m, 2H), 6.49 ppm (d, 2H, J = 6.9 Hz), 7.05 ppm (m, 3H), 7.40 ppm (m, 4H), 7.77 ppm (t, 2H, J = 7.56 Hz), 7.89 ppm (t, 2H, J = 7.37 Hz)
13C RMN, (DMSO-d6, 300MHz) δ: 15.8, 35.5, 46.8, 66.1, 68.0, 112.2, 120.5, 120.6, 125.0, 125.1, 127.1, 127.6, 128.1, 129.3, 134.0, 141.3, 141.5, 143.8, 144.0, 150.2, 163.4, 178.6, 195.4
Figure 1S. LC Chromatogram of crude compound 5.
Figure 2S. LC Chromatogram and ES+ Mass spectrum of purified compound 5.
Figure 3S. LC Chromatogram and ES+ Mass spectrum of purified compound 7.
Figure 4S. LC Chromatogram and ES+ Mass spectrum of purified pseudopeptide 2.
Figure 5S. 1H and 13C NMR of compound 5.
Figure 6S. 1H and 13C NMR of compound 7.