Diazomethane → (1R,2S)-ethyl 1-(tert-butoxycarbonylamino)-2-cyclopropylcyclopropanecarboxylate

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Reaction Steps

A solution of N-Boc-(1R,2S)-1-amino-2-vinylcyclopropane carboxylic acid (255 mg, 1.0 mmol) in diethyl ether (10 mL) was treated with palladium acetate (5 mg, 0.022 mmol). The orange/red solution was placed under a nitrogen atmosphere. An excess of diazomethane in diethyl ether was added dropwise over the course of 1 hour. The resulting solution was stirred at room temperature for 18 hours. The excess diazomethane was removed using a stream of nitrogen and the resulting solution was concentrated by rotary evaporation to give the crude product. Flash chromatography (10% ethyl acetate/hexane) provided 210 mg (78%) of (1R,2S)—N-Boc-1-amino-2-cyclopropylcyclopropane carboxylic acid ethyl ester as a colorless oil. LC-MS (retention time: 2.13, similar to method A except: gradient time 3 minutes, Xterra MS C18 S7 3.0×50 mm column), MS m/e 270 (M++1).

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