Water → 1-[(tert-butoxy)carbonyl]-3-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)azetidine-3-carboxylic acid

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Reaction Steps

A round bottomed flask was charged with 3-amino-1-(tert-butoxycarbonyl)azetidine-3-carboxylic acid (prepared according the procedure described in Synthesis 1991, 783-784.) (2.464 mmol), sodium carbonate (1.3 g, 12.32 mmol), a stir bar and water (70 mL). (9H-fluoren-9-yl)methyl carbonochloridate (1.9 g, 7.39 mmol) in 1,4-dioxane (50 mL) was added and the milky solution was stirred overnight at rt. The next day the reaction was poured into a separatory funnel and the aqueous solution washed with diethyl ether (repeated twice) (organic phases were discarded at this stage). The aqueous phase was acidified to pH 2-3 with 1 M HCl (a precipitate was formed) and the product was extracted with EtOAc (repeated 3 times). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated to dryness. The solid was used without purification in the next step. LRMS (M+Na)+: 461 m/z.

Provenance & Evidence