1-Ethyl-3-(3'-dimethylaminopropyl)carbodiimide → (S)-methyl 4-(tert-butoxycarbonylamino)-5-((S)-1-(4-iodobenzylamino)-5-methoxy-1,5-dioxopentan-2-ylamino)-5-oxopentanoate

Participants

Reaction Steps

A solution of (S)-methyl 4-(tert-butoxycarbonylamino)-5-(4-iodobenzylamino)-5-oxopentanoate (2.129 g, 4.47 mmol) in DCM (15 mL) and TFA (10 mL) was stirred at room temperature for 4 h. After the solvent was evaporated, the reaction mixture was diluted with DCM, washed with sat. K2CO3 aqueous solution and concentrated in vacuo to afford (S)-methyl 4-amino-5-(4-iodobenzylamino)-5-oxopentanoate (1.67 g). A solution of (S)-methyl 4-amino-5-(4-iodobenzylamino)-5-oxopentanoate (1.67 g), Boc-Glu(OMe)—OH.DCHA (1.97 g, 4.44 mmol), EDCI (1.02 g, 5.33 mmol), HOBt (0.599 g, 4.44 mmol) in DCM (100 mL) containing DIPEA (2.26 mL) was stirred at room temperature under nitrogen for 20 h. The reaction mixture was diluted with DCM, washed with 1N HCl aqueous solution, sat. NaHCO3 aqueous solution and brine. The organic phase was separated and evaporated under reduced pressure to give a crude product, which was purified by flash chromatography with hexane/ethyl acetate as eluent to give (S)-methyl 4-(tert-butoxycarbonylamino)-5-((S)-1-(4-iodobenzylamino)-5-methoxy-1,5-dioxopentan-2-ylamino)-5-oxopentanoate (2.137 g, 77% over 2 steps) as a white solid. 1H NMR (400 MHz, CDCl3) δ 7.62 (d, J=8.4 Hz, 2H), 7.20 (s, 1H), 7.00 (d, J=8.4 Hz, 2H), 5.44 (brs, 1H), 4.48-4.30 (m, 3H), 4.06-4.02 (m, 1H), 3.69 (s, 6H), 2.54-2.37 (m, 4H), 2.20-1.93 (m, 3H), 1.37 (s, 9H); MS (ESI), 620 (M+H)+.

Provenance & Evidence