Silyl nitronates spectroscopy

Despite the potential for geometrical isomers, in almost aU cases, a single set of signals is observed by both and NMR spectroscopy for silyl nitronates. This... 

In the solution state, the possibility of a pentacoordinate silicon species can also be discounted by Si NMR spectroscopy (29). Comparison of the silyl nitronates 14 and 6 to the corresponding silyl oximes 15 and 16 show that the silicon resonances are almost identical (Fig. 2.4). If there were a significant interaction with both oxygens in the nitronate, the resonance would be shifted from that of the silyl oxime. 

The C,C-coupling reactions of six-membered cyclic nitronates were studied in most detail (274, 478). Here silyl ketene acetal was also used as the test nucleophile. The configurations of most of the starting nitronates and the resulting nitroso acetals were determined by NMR spectroscopy and X-ray diffraction, and also a conformational analysis was performed (see Tables 3.24 and 3.25). 

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