H20
Ethyl 3-(2-(3,4-dimethoxyphenyl)acetamido)benzoate (4): Compound 4 was synthesized according to the general procedure (but extracted with CH2Cl2 instead of EtOAc), using 2-(3,4-dimethoxyphenyl)acetic acid (0.20 g, 1.02 mmol) and was obtained as a yellow solid (0.28 g, 0.83 mmol, 81 %). 1 H NMR (500 MHz, CDCl3): ?=7.91–7.84 (m, 2H), 7.74 (d, J=7.7 Hz, 1H), 7.49 (d, J=7.2 Hz, 1H), 7.35 (t, J=7.8 Hz, 1H), 6.89–6.84 (m, 2H), 6.83 (s, 1H), 4.33 (q, J=7.1 Hz, 2H), 3.88 (s, 3H), 3.87 (s, 3H), 3.68 (s, 2H), 1.35 (t, J=7.1 Hz, 3H); 13 C NMR (126 MHz, CDCl3): ?=, , , , , , , , , , , , , , , , , ; HRMS (ESI + ) [M+H] + C19Htwenty twoNO5 calculated Da, found: m/z.
Ethyl 3-(2,4-bis-(benzyloxy)benzamido)benzoate (21): Compound 21 was synthesized according to the general procedure, using 16 (0.06 g, 0.18 mmol) and was obtained as a brown solid (0.02 g, 0.04 mmol, 20 %). 1 H NMR (400 MHz, CDCl3): ?=9.92 (s, 1H), 8.30 (d, J=8.7 Hz, 1H), 7.94 (s, 1H), 7.71 (d, J=7.7 Hz, 1H), 7.61–7.21 (m, 12H), 6.77 (d, J=9.0 Hz, 1H), 6.73 (s, 1H), 5.19 (s, 2H), 5.14 (s, 2H), 4.37 (q, J=7.1 Hz, 2H), 1.39 (t, J=7.1 Hz, 3H).
Ethyl 3-(3,4-bis-(benzyloxy)benzamido)benzoate (22): Compound 22 was synthesized according to the general procedure using 17 (0.10 g, 0.30 mmol), but was not extracted. Instead the solvent of the reaction mixture was evaporated under reduced pressure and the residue directly purified by column chromatography. The desired product was obtained as a yellow solid (0.14 g, 0.28 mmol, 93 %). 1 H NMR (400 MHz, CDCl3): ?=8.09 (s, 1H), 8.03 (d, J=8.1 Hz, 1H), 7.99 (s, 1H), 7.80 (d, J=7.7 Hz, 1H), 7.55 (d, J=2.0 Hz, 1H), 7.48–7.27 (m, 12H), 6.93 (d, J=8.4 Hz, 1H), 5.21 (s, 2H), 5.19 (s, 2H), 4.36 (q, J=7.1 Hz, 2H), 1.38 (t, J=7.1 Hz, 3H).
Ethyl 3-(3,5-bis-(benzyloxy)benzamido)benzoate (23): Compound 23 was synthesized according to the general procedure (but extracted with CH2Cl2 instead of EtOAc), using 18 (0.17 g, 0.50 mmol) and was obtained as a white solid (0.09 g, 0.02 mmol, 36 %). m/z (ESI + ) [M+H] + C30H28NO5 calculated 482.2 Da, found: 482.8 m/z.
General procedure for the preparation of compounds 1,3, and 6 via O-benzyl-deprotection: To a mixture of the respective O-benzyl-protected compounds in THF/MeOH (1 : 1 v/v, 30 mL mmol ?1 ) was added palladium on active carbon (20 w%). The resulting suspension was stirred at room temperature for 8 h under H2 atmosphere (1 bar) and then filtered over Celite. 2 (hexane/EtOAc as eluent) to afford the desired compounds 1, 3 and 6.