Five-membered Nitrogen- and Oxygen-containing Rings

Five-membered Nitrogen- and Oxygen-containing Rings. Huisgen et al. have generated benzonitrile-4-nitroben lide (102) in small equilibrium concentrations. This is the first representative of a class of nitrile ylides and 

Aldimines and ketimines react with benzonitrile oxide to give A -oxadia-zolines (111) in good yields, and 2,4,6-trimethylbenzonitrile oxide combines with phenyl isocyanate to give a 1,2,4-oxadiazolin-5-one (112). 2 Nitrile oxides are also used in the preparation of 1,3,4-dioxazoles (113) from carbonyl 

The C=N bond in 2-isoxazolines of the form (114) undergoes a 1,3-dipolar cycloaddition with benzonitrile oxide, giving rise to a variety of new heterocyclic systems (115) whose structures were established by both spectral and chemical methods.  

2-Acetoacetyl-5-benzoyl-l-phenylpyrrolidin-3-one (116) is synthesized by the cycloaddition of the nitrone (117) to diketen. The reaction involves intramolecular rearrangement of the initial adduct (118) followed by aceto-acetylation.  

A further report has appeared of the synthesis of TV -alkoxyisoxazolidines from nitrones and activated olefins.  

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