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Cycloaddition/Ring opening of 3-unsubstituted cyclic nitronates, isoxazoline and 5,6-dihydro-4H-1,2-oxazineN-oxides, as synthetic equivalents of functionalized nitrile oxides

✍ Scribed by Shuji Kanemasa; Takanori Yoshimiya; Eiji Wada

Publisher: Elsevier Science
Year: 1998
Tongue: French
Weight: 273 KB
Volume: 39
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(98)01903-0

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✦ Synopsis

o)-Halo-~-nitropropane and -butane are cyclized with a base to form cyclic nitronates as labile 1,3-dipoles. They can be trapped by a variety of monosubstituted ethenes to give 3-(2hydroxyethyl)isoxazolines or perhydroisoxazolo[2,3-b]o-oxazines depending upon the ring size of nitronates. The latter ring-fused heterocycles are transformed by treatment with an acid into 3-(3hydroxypropyl)isoxazolines in good yields. Therefore, these cyclic nitronates are useful synthetic equivalents of functionalized nitrile oxides. Isolation of 5,6-dihydro-4H-1,2-oxazine N-oxide and their regio-and stereoselective cycloadditions are also discussed.

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