Citric Acid → 4-(4-(((2-((Tert-butoxy)carbonylamino)-1-(methoxycarbonyl)ethyl) amino)sulfonyl)-3,5-dimethylphenoxy)butanoic acid

Participants

Reaction Steps

A solution of the 4-(chlorosulfonyl)-3,5-dimethylphenoxybutanoic acid, 18 (2.50 g, 8.1 mmol) in dioxane (60.0 g) was added dropwise over a period of about 45 minutes to a mixture of H-Dap(Boc)-OMe.HCl (19) (1.66 g, 6.5 mmol) (Bachem) and NaHCO3 (8.21 g, 97.7 mmol) in water (20.0 g) at rt. Two hours after completion of the addition, the reaction mixture was concentrated in vacuo then water and citric acid (12.50 g, 10.0 eq.) were added. The crude product was extracted with EtOAc and the EtOAc layer was washed once with water. Concentration of the EtOAc layer gave 2.75 g of 20 (87% yield based on 19, 69% based on 18).

Provenance & Evidence