Nitrones structure

For this purpose, nitronate (107) containing the EtSCO- fragment was synthesized followed by selective saponification of this fragment with mercury acetate in water, which occurred with retention of the nitronate structure. 

The intramolecular cycloadditions of cychc nitronates have received much more attention. The cyclic nitronate structure provides three basic modes of intramolecular cycloaddition (Fig. 2.15). Attachment of the tether to the C(3) position of the nitronate results in the formation of a sprro system (sprro mode). However, if the tether is appended to the C(4) position of the nitronate, the dipolar cycloaddition yields a fused ring system (fused mode). Finally, if the tether is attached at any other point of the cyclic nitronate, the cycloadducts obtained will consist of bicyclic structures (bridged mode). 

For alkenes substituted with longer fluoroalkyl chains, yields and regioselectivities are not so dependent on nitrone structure. ... 

The isoxazolidines 87 were isolated in good to excellent cwdlo-selectivity, high yields, and high ee. The reaction appears quite general with respect to the nitrone structure, and X = alkyl, allyl, or benzyl was tolerated without loss of yield or selectivity. 

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