Phenyl isocyanate → Methyl 3-[2-(4'-fluoro-3,3',5-trimethyl[1,1'-biphenyl]-2-yl)ethyl]-4,5-dihydro-5-isoxazoleacetate

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Reaction Steps

A solution of 0.1 g (1.0 mmol) of methyl 3-butenoate and 0.174 ml (1.6 mmol) of phenyl isocyanate in 1 ml of toluene was added with stirring to a solution of 0.240 g (0.8 mmol) of the nitropropyl compound from Step D and 2 drops of triethylamine in 1 ml of toluene. The resulting mixture was stirred at room temperature for 3 hours. Additional quantities of methyl 3-butenoate (0.1 ml), triethylamine (0.1 ml) and phenyl isocyanate (0.15 ml) were added successively and stirring was continued overnight (18 hours). The mixture was filtered and the filtrate was concentrated in vacuo to a residue which was purified by flash chromatography on silica gel (230-400 mesh), first being eluted with methylene chloride to remove the impurities. Continued elution with acetone/methylene chloride (1:50, v/v) gave the desired product (0.218 g, 0.57 mmol, 71%) as a pale viscous oil. nmr (CDCl3) δ: 2.28 (6H, s), 2.32 (3H, s), 2.2-3.0 (6H, m), 3.70 (3H, s), 4.6-5.0 (H, m), 6.85 (H, bs), 7.0-7.2 (4H, m). IR (neat) 1735 cm-1

Provenance & Evidence