化合物31－34作为氟代试剂，在碱性条件下作用于羰基化合物，由于立体位阻的影响，往往能得到立体选择性的α-氟代羰基化合物，但其ee%不是太高。

Under an argonatmosphere, to a solution of 2-Oxo-cyclopentanecarboxylic acid ethyl ester (1.56 g, 10 mmol) in dry ether (20 mL) wasadded 60% NaH (0.48 g,12 mmol) at 0^oC, the mixture was stirred for 30 min, N-fluoro sultam(-)-31 (3.5 g,15 mmol) was added in several portions. The reaction mixture was stirred for another 1 h at room temperature,then quenched by saturated NH₄Cl solution, and extracted withEA.  The combined organic layer was driedover Na₂SO₄, concentrated under reduced pressure.  Theresidue was purified by column chromatography on silica gel to give the desiredproduct (1.09 g, 63%, 70% ee).

【Differding, E; Lang, R, W. Tetrahedron. Lett. 1988, 29, 6087.】

如果底物是手性的，也能得到高选择性的对映异构体。

【Davis, F, A; Han, W. Tetrahedron. Lett. 1992, 33, 1153】

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