摘要：

Silyl nitronates of 2,2,2-trifluoronitroethane and of 1,1,1-trifluoro-2-nitropropane [SiMe3, SiMe2(tBu), SiMe2CMe2-CHME2] were prepared and their reactions studied. – The TBDMS nitronate of the nitroethane is present at the (E) and (Z) isomer (2.3:1 at room temperature; EA = 9.3 kcal mol1 for their isomerization). BU4NF-catalyzed silyl nitro aldol additions to aldehydes show reasonable selectivities for the formation of the syn diastereoisomers of 5–13 (a. 4:1; with the non-fluorinated analogs anti isomers prevailing!). The anti epimers (5–9, 12, 13, 17–20) in the trifluoromethyl series can be prepared by diastereoselective protonation of the corresponding O-silyl lithium nitronates (ca. 9:1, Scheme 3). Careful reduction of the NO2 groups (H2/Raney nickel) gives trifluoroamino alcohol derivatives (22–30, Scheme 4). –The trimethylsilyl nitronates are also used for 1,3-dipolar cycloadditions (to 1-hexene, styrene, methyl vinyl ketone, and acrylates) to give N-(silyloxy)isoxazolidines (2–40; Scheme 5). The configuration of the major products (2,3-cis, 3,5-trans) was derived from NMR measurements, X-ray structure determinations, and thermal equilibration studies. The major course of reactions was thus derived to be an exo approach of the dipolarophiles to the (Z)-silyl nitronates (Scheme 8).– Some conversions of the N-(silyloxy)isoxazolidines (treatment with acid, base, and Raney nickel) are also described (products 42–51).

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