Triphenylphosphine → ethyl 3-(2-fluoro-4-{(4-hydroxy-2,3-dihydro-1H-inden-1-yl)[(2-nitrophenyl)sulfonyl]amino}phenyl)propanoate

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Reaction Steps

A solution of ethyl 3-(2-fluoro-4-{[(2-nitrophenyl)sulfonyl]amino}phenyl)propanoate (20.0 g, 50.5 mmol), 4-{[tert-butyl(dimethyl)silyl]oxy}indan-1-ol (14.7 g, 55.6 mmol) and triphenylphosphine (14.6 g, 55.6 mmol) in tetrahydrofuran (300 mL) was stirred under ice-cooling, and diethyl azodicarboxylate (40% toluene solution, 25.3 mL, 55.6 mmol) was added. The mixture was allowed to warm to room temperature and stirred for 16 hr. To the reaction mixture were added reagents (4-{[tert-butyl(dimethyl)silyl]oxy}indan-1-ol, triphenylphosphine and diethyl azodicarboxylate) in a half amount of the above, and the mixture was further stirred for 4 hr. The reaction mixture was concentrated, and diethyl ether and hexane were added to the residue. The resultant insoluble material was filtered off and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=95/5-hexane/ethyl acetate=30/70) to give a yellow oil. To a solution of the obtained oil in tetrahydrofuran (250 mL) was added tetrabutylammonium fluoride (1 M THF solution, 61.1 mL, 61.1 mmol) under stirring under ice cooling and the mixture was stirred at the same temperature for 3 hr. Ethyl acetate was added to the reaction mixture, and the mixture was washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=70/30-hexane/ethyl acetate=30/70) to give the title compound (21.5 g, yield 81%, 2 steps) as a yellow oil.

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