Sulfuric Acid → Rac-5-amino-2-propylpentanoic acid 1,1-dimethylethyl ester

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Reaction Steps

To a cooled solution of 7 mL of dioxane was added 0.7 mL of conc. H2SO4 dropwise. The solution turned purple in color. To this solution, 700 mg (3.5 mmol) of 5-amino-2-propylpentanoic acid monohydrochloride (7) was slowly added and the resulting solution was transferred into a pressure bottle. To this solution was added 12 mL of isobutylene and the resulting solution was slowly stirred magnetically under pressure at room temperature for 20 hours. The reaction vessel was cooled in dry ice, pressure was released, and the reaction vessel warmed up to room temperature to vaporize the excess isobutylene. The reaction mixture was poured into 100 mL of cold water. The aqueous part was extracted with 2×150 mL of ether, basified with 4N sodium hydroxide to pH 10, and extracted with 3×100 mL of ethyl acetate to yield 380 mg (1.76 mmol, 49%) of rac-5-amino-2-propylpentanoic acid 1,1-dimethylethyl ester (8) as an oil. NMR, IR and MS data confirmed the compound identity.

Provenance & Evidence