A mixture of 4-(tert-butyldimethylsilyloxymethyl)-1-(triphenylmethyl)imidazole, as described above in Step D, (485 mg, 1.07 mmol), 1-(4-cyano-3-fluorophenyl)ethanol, as described above in Step C, (160 mg, 0.969 mmol), and N,N-diisopropylethylamine (0.219 mL, 1.26 mmol) in CH2Cl2 (12 mL) was cooled to −78° C., under argon. Trifluoromethanesulfonic anhydride (0.196 mL, 1.17 mmol) was added dropwise, and the mixture was stirred for 18 hours while it slowly warmed to ambient temperature. Methanol (15 mL) was added and the CH2Cl2 was distilled off in vacuo. The resulting methanolic solution was heated to reflux for 3 hours, then concentrated in vacuo to give a residue which was partitioned between saturated aqueous Na2CO3 (10 mL) and CH2Cl2 (20 mL). The aqueous layer was extracted further with CH2Cl2 (20 mL). The combined organic extracts were dried over Na2SO4, filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography, eluting with a gradient of CH2Cl2—0% to 5% MeOH, to yield the titled product as a pale foam.
