Water → N-Boc-4-(2'-bromoisobutyramido)phenylalanine

Participants

Reaction Steps

Commercially available N-Boc 4-aminophenylalanine (3.62 g, 0.01447 mol) was dissolved in 50 mL of dry THF. 2-bromoisobutyryl bromide (1.757 mL, 0.01422 mol) was added dropwise over 30-60 seconds with vigorous stirring. The reaction was complete after 10 min (monitored by TLC). After approximately 20 min. the entire reaction mixture (including newly formed precipitate) was transferred to a separatory funnel with CHCl3, and approximately 100 mL of H2O. The reaction mixture was extracted with CHCl3 (3×50 mL). The organic phase was washed with distilled water (2×50 mL) and brine (50 mL). The organic phase was dried with MgSO4 and evaporated in vacuo to obtain the crude product (4.55 g). The crude solid product was recrystallized in 20-30 mL acetonitrile three times to purify the product. After three recrystallizations, N-Boc-4-(2′-bromoisobutyramido)phenylalanine was obtained in 65% yield (3.63 g). 1H NMR (500 MHz, DMSO): δ9.4 (s, 1H, COOH), δ7.8 (s, 1H, NH), δ7.5 (d, 2H, Ar H), δ7.1 (d, 2H, Ar H), δ6.0 (d, 1H, NH), δ4.2 (d, 1H, CH), δ3.05 (dd, 2H, CH2), δ2.0 (s, 6H, CH3), δ1.3 (s, 9H, CH3).

Provenance & Evidence