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 0oC, 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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