Nitrogen → ethyl (2R,3S)-3-phenylaziridine-2-carboxylate

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The title compound was synthesized using a literature method (Legters, J.; Thijs, L.; Zwanenburg, B. Tetrahedron Lett. 1989, 30, 4881). To a mixture of 3-phenyloxirane-2-carboxylic acid ethyl ester (9.6 ml, 55 mmol) and 183 ml of EtOH in a flame-dried two-necked flask equipped with a water condenser and magnetic stirring rod was added NaN3 (10.73 g, 165 mmol) and ammonium chloride (8.83 g, 165 mmol). The reaction mixture was brought to 65° C. and stirred for 5 hours at which point GC analysis showed that the reaction was complete. The mixture was filtered and concentrated under reduced pressure. The crude 1H NMR showed that the product of nucleophilic opening of the epoxide by azide was pure enough to carry over to the next step. In a flame-dried two-neck flask fitted with a water condenser and equipped with a magnetic stirring bar was added the product from above (12.93 g, 55 mmol) dissolved in 183 ml of acetonitrile. The reaction mixture was brought to 40° C., at which point PPh3 (16 g, 61 mmol) was added slow enough to avoid rapid evolution of N2. The reaction was then brought to 83° C. and stirred for 5 hours. The reaction mixture was then cooled and concentrated under reduced pressure. The crude mixture was then dissolved in 5% EtOAc in pentane and filtered. The filtrate was concentrated and subsequently dissolved in pentane and placed in the freezer overnight (−15° C.). Any resulting precipitate that formed was filtered off and the filtrate was concentrated under reduced pressure and subjected to silica gel column chromatography (eluent 20% EtOAc in hexanes) to yield a pale yellow oil in 61% over two steps. 1H NMR (200 MHz. CDCl3) (δ: 7.36-7.25 (m, 5H), 4.25 (qd, J=7 Hz, 1.2 Hz, 2H), 3.25 (s, 1H), 2.58 (s, 1H), 1.89 (bs, 1H), 1.31 (t, J=7 Hz, 3H) ppm. 13C NMR (75 MHz. CDCl3) δ: 171.6, 137.8, 128.3, 127.6, 126.1, 61.6, 40.2, 39.3, 14.0 ppm.

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