Triphenylphosphine → 5-Ethyl-2-[3-[2,6-dimethyl-4-(2-methyl-tetrazol-5-yl)-phenoxy]-propyl]furan

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Reaction Steps

Diethyl azodicarboxylate (DEAD, 4.84 g; 27.8 mmol) was added under nitrogen to a stirred and cooled (-20° C.) solution of triphenylphosphine (7.37 g; 27.8 mmol), 5-ethyl-2-(3-hydroxypropyl)furan (Intermediate 1c) (3.9 g; 25.3 mmol), and 4-(2-methyl-tetrazol-5-yl)-2,6-dimethylphenol (5.69 g; 27.8 mmol). The mixture was stirred at -20° C. for 1/2 h, and then was allowed to warm to room temperature overnight. Water (50 mL) was added to the mixture and the layers were separated. The aqueous layer was extracted with ether (3×50 mL), the organic layer was washed with 10% NaOH solution (3×50 mL), water, and dried over magnesium sulfate. The solvent was concentrated in vacuo to yield a residue and purified by MPLC column chromatography (ethyl acetate/hexane, 3:7) to afford 5.63 g (65%) of 5-ethyl-2-[3-[2,6-dimethyl-4-(2-methyl-tetrazol-5-yl)-phenoxy]-propyl]furan (Formula II; R3 =5-ethyl, R4 =hydrogen, R1, R2 =3,5-dimethyl, R5 =2-methyltetrazol-5-yl, Y=1,3-propylene).

Provenance & Evidence