N-(Diphenylmethylene)glycine tert-butyl ester → 2-(Benzhydrylidene-amino)-3-cycloheptyl-propionic acid tert-butyl ester

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Reaction Steps

To a stirred solution of (Benzhydrylidene-amino)-acetic acid tert-butyl ester (2.56 g; 8.68 mmol) in 30 mL of tetrahydrofuran under argon at −78° C. was added lithium diisopropylamide solution (10.0 mL; 1.5 M solution in cyclohexane) dropwise. After 30 minutes, a solution of cycloheptylmethyl iodide (Prepared in Step B; 3.48 g; 14.6 mmol) in 20 mL tetrahydrofuran was added dropwise and the mixture allowed to warm to room temperature and stirred for 18 h. The mixture was quenched with saturated ammonium chloride solution (100 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate. The combined organic layers were dried (sodium sulfate) filtered and concentrated in vacuo. The crude product was chromatographed (Biotage 40M; eluent: 5% ethyl acetate/hexanes) to give 2.56 g (73%) of 2-(Benzhydrylidene-amino)-3-cycloheptyl-propionic acid tert-butyl ester as a pale yellow oil.

Provenance & Evidence