To a solution of methyl 2-docosa-4,7,10,13,16,19-hexaenamido-4-methylpentanoate (610 mg, 1.34 mmol) in MeOH (15 mL) was added 2 M NaOH (30 mL). The reaction mixture was heated (50° C., 16 h), cooled (RT), and acidified with 2 M HCl to pH=1. The mixture was extracted with EtOAc (3×50 mL). The combined organic layers were washed with brine, dried over MgSO4, and concentrated under reduced pressure. The crude product was purified by silica chromatography, (MeOH:DCM, 0-10%) to afford 2-docosa-4,7,10,13,16,19-hexaenamido-4-methylpentanoic acid (0.51 g, 89%) as a light yellow solid. Mass calculated for C28H43NO3=441.65. found: [M+H]+=442.1.
