Dicyclohexylcarbodiimide → (E)-2-Phenylbut-2-enyl 2-(2,2,2-Trifluoroacetamido)acetate

Beteiligte Stoffe

Reaktionsschritte

To a suspension of N-trifluoroacetylglycine (11, 3.68 g, 21.50 mmol) and (E)-2-phenyl-2-buten-1-ol (12, 2.68 g, 19.32 mmol) in DCM (60 mL) at −40° C. under N2 was added via cannula a solution of dicyclohexylcarbodiimide (4.43 g, 21.50 mmol) and 4-dimethylaminopyridine (0.269 g, 2.15 mmol) in DCM (60 mL). The solution was stirred at ambient temperature for 18 h and filtered, and the precipitate was washed with DCM (2×40 mL). The combined filtrate and washing was washed with 10% citric acid (2×25 mL), H2O (10 mL), 6% NaHCO3 (2×25 mL), and 5 M NaCl (20 mL), and dried, and the solvent was evaporated. The residue was chromatographed (silica gel, 150 g; 4:1 hexane-EtOAc) to afford 5.06 g (87%) of 13 as a pale yellow oil that solidified on standing: mp 49-50° C.; Rf0.66 (4:1 hexane-EtOAc); 1H NMR δ 7.37 (2H, t, J=7.5 Hz), 7.30 (1H, t, J=7.2 Hz), 7.18 (2H, d, J=7.6 Hz), 6.75 (1H, br s), 5.95 (1H, q, J=6.9 Hz), 4.91 (2H, s), 4.06 (2H, d, J=4.9 Hz), 1.66 (3H, d, J=6.9 Hz); 13C NMR δ 167.9, 156.7 (m), 137.3, 135.4, 135.4, 128.5, 128.4, 127.4, 116.9, 70.8, 41.4, 14.6; MS APCI+ m/z 302.1026 [M+H]+ (calcd for C14H15F3NO3, 302.1004); anal. C, 55.73, H, 4.93, N, 4.67%, calcd for C14H14F3NO3, C, 55.82, H, 4.68, N, 4.65%.

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