0.383 g of 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one was added to a solution of 0.285 g of 3(S)-(tert-butoxyformamido)-2(S)-hydroxy-N-(1(S)-phenylpropyl)heptanamide in 20 ml of dichloromethane. The mixture was stirred at room temperature for 30 minutes and then a further 30 mg of 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one were added. The mixture was stirred at room temperature for 30 minutes and then diluted with ethyl acetate. The solution was extracted with a solution of 10 g of sodium thiosulphate in 40 ml of saturated sodium bicarbonate solution. The aqueous layer was extracted with ethyl acetate and the combined organic layers were washed with water, dried over magnesium sulphate and evaporated. The residue was purified by chromatography on silica gel using 20% ethyl acetate in hexane for the elution to give 200 mg of 3(S)-(tert-butoxyformamido)-2-oxo-N-(1(S)-phenylpropyl)heptanamide, MS: m/e 377.1 [M+H]+.
