3-Oxo-azetidine-1-carboxylic acid tert-butyl ester → tert-Butyl 3-methylideneazetidine-1-carboxylate

Participants

Reaction Steps

To a 0° C. mixture of KOtBu (5.90 g, 52.6 mmol) in 95 mL ether was added methyltriphenylphosphonium bromide (18.8 g, 52.6 mmol). The reaction mixture was warmed to ambient temperature and stirred 1.5 hours. A solution of tert-butyl 3-oxoazetidine-1-carboxylate (4.50 g, 26.3 mmol) in 10 mL ether was added. The reaction mixture was heated to reflux for 2 hours, then cooled to ambient temperature. Solids were removed by vacuum filtration through compressed Celite and rinsed with ether, and the filtrate was concentrated. The resulting residue was suspended in 1:1 hexanes:ethyl acetate, and the solids were removed by vacuum filtration through GF/F paper and rinsed with 1:1 hexanes:ethyl acetate. The filtrate was concentrated, and the resulting oil was purified on silica gel (5-20% ethyl acetate in hexanes gradient) to give the desired product (3.50 g, 78.7% yield) as a clear colorless oil.

Provenance & Evidence