N-(Diphenylmethylene)glycine tert-butyl ester → 2-(Benzhydrylidene-amino)-3-(2-fluoro-5-methoxy-phenyl)-propionic acid tert-butyl ester

Participants

Reaction Steps

KHMDS (550 μl of a 0.5 M solution in toluene, 0.55 mmol) diluted with dry THF (1.5 mL) was added to a solution of t-butylglycinate Schiff base 3 (68 mg, 0.23 mmol) in THF (1.5 mL). A mixture containing 2-fluoro-5-methoxybenzyl bromide (35, 50 mg, 0.23 mmol) in THF (1.0 mL) was immediately added to the resulting enolate solution at −78° C. The combined mixture was warmed to room temperature, stirred for 2 h, diluted with 1:1 ether/pentane (20 mL), washed with brine (3×10 mL), dried (sodium sulfate), filtered and then concentrated to afford 40 as a crude yellow oil (115%). Interestingly, a lower yield of 22% (40 mg) was obtained compared to using LiHMDS.

Provenance & Evidence