Nitrile oxide-olefin cycloaddition reactions deliver heterocyclic products with a wide variety of functionality and provide a particularly powerful means of preparing substituted isoxazoles by the intermolecular 1,3-dipolar cycloaddition of a nitrile oxide with a monosubstituted alkyne to give a preponderance of the 3,5-disubstituted isoxazole. In this study, an extension of the intramolecular nitrile oxide-olefin cycloaddition reaction is reported for the facile synthesis of furo[3,4-c]isoxazoles (5) which are in turn shown to be useful precursors to 3,4-disubstituted or 3,4,5-trisubstituted isoxazole derivatives (6). The method consists of a high-yield preparation of a broad spectrum of furo[3,4-c]isoxazoles by intramolecular nitrile oxide-alkyne cycloaddition of acetylenic nitro ethers (3), in turn prepared by Michael addition of various propargylic alkoxides (2) to appropriate nitro olefins (1).
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Organic Chemistry|
|State||Published - 1992|
ASJC Scopus subject areas
- Organic Chemistry