1,2,4-Oxadiazole 4-oxides display nitronic reactivity and selectivities identical to those of N-methyl-C-phenyl nitrone, which is a typical acyclic nitrone, affording comparable amounts of endo- and exo-5-alkoxyisoxazolidines. The exo stereoisomers undergo an easy rearrangement under the reaction conditions to yield oxadiazolinic esters. The structures of the adducts have been confirmed by X-ray structures and spectroscopic data. A donor p-methoxyphenyl at the nitronic carbon slows down the cycloaddition rate, while an acceptor p-nitrophenyl retards the rearrangement of the exo adduct.
1,2,4-Oxadiazole-4-oxides as nitrones in 1,3-dipolar cycloaddition reactions to vinyl ethers
QUADRELLI, PAOLO;BOVIO, BRUNA;CARAMELLA, PIERLUIGI
2012-01-01
Abstract
1,2,4-Oxadiazole 4-oxides display nitronic reactivity and selectivities identical to those of N-methyl-C-phenyl nitrone, which is a typical acyclic nitrone, affording comparable amounts of endo- and exo-5-alkoxyisoxazolidines. The exo stereoisomers undergo an easy rearrangement under the reaction conditions to yield oxadiazolinic esters. The structures of the adducts have been confirmed by X-ray structures and spectroscopic data. A donor p-methoxyphenyl at the nitronic carbon slows down the cycloaddition rate, while an acceptor p-nitrophenyl retards the rearrangement of the exo adduct.File in questo prodotto:
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