4-Aminobenzoic Acid → HCID 131726467, compound

Participants

Reaction Steps

To a solution of 156 mg (194 μmol) of compound 16 and 26.3 mg (1.1 eq.) PABA in dry N,N-dimethyl formamide under an Argon atmosphere was added diisopropylethyl amine (34 μl, 1.0 eq.) and a catalytic amount of N-hydroxybenzotriazole (7.9 mg, 0.3 eq.). The reaction solution was stirred for 24 hours after which it was diluted with 10% propanol-2/EtOAc. The organic layer was washed with saturated sodium bicarbonate, 0.5 N potassium hydrogensulfate and brine, dried over anhydrous sodium sulfate and evaporated to dryness. The yellow residual film was purified by means of column chromatography (SiO2—CHCl3/MeOH 9/1) to yield 148 mg (97%) of the desired product 17. M.P. 196–197° C.; 1H-NMR (300 MHz, CDCl3): δ 1.20 (d, 3H, 3J=6.4 Hz, CH3-Ala), 1.27–2.05 (m, 6H, 3 CH2-Lys), 2.99 (dd, 1H, benzylic), 3.14 (m, 2H, N—CH2-Lys), 3.27 (dd, 1H, benzylic), 4.00–4.64 (m, 7H, 3 Hα and Aloc), 4.57 (s, 2H, benzylic-spacer), 5.14 (s, 2H, benzylic-spacer), 5.06–5.37 (m, 4H, Aloc), 5.72 (m, 1H, Aloc), 5.88 (m, 1H, Aloc), 7.10–7.46 (m, 11H, aromatic), 7.64 (d, 2H, 3J=8.3 Hz, aromatic) ppm; MS (FAB) m/e 809 (M+Na)+;; C41H50N6O10 (.½H2O) calculated C 61.87%; H, 6.46%; N, 10.56%; measured C, 61.84%; H, 6.38%; N, 10.38%.

Provenance & Evidence