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

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Reaction Steps

A mixture of potassium tert-butoxide (15.5 g, 137 mmol) and methyltriphenylphosphine bromide (49 g, 137 mmol) in diethyl ether (300 mL) was stirred at room temperature for 1 hour, followed by the addition of 1,1-dimethylethyl 3-oxoazetidine-1-carboxylate (10 g, 58 mmol in 100 mL diethyl ether). The mixture was stirred at 35° C. for 2 hours and then allowed to cool to room temperature. The mixture was filtered through a pad of celite, washing with diethyl ether. The filtrate was partitioned with water and washed twice with water, brine, dried over sodium sulfate, filtered and concentrated in vacuo to give an orange oil which was purified by column chromatography. Eluting with 10% ethyl acetate in hexanes, isolated product was concentrated in vacuo to afford 9.80 g, 58 mmol (100%) of 1,1-dimethylethyl 3-methylideneazetidine-1-carboxylate as a colorless oil. 1H NMR (400 MHz, DMSO): 5.05-4.85 (m, 2H), 4.95-4.63 (m, 4H), 1.45 (s, 9H). GC-MS for C9H15NO2: 169.

Provenance & Evidence