ChemInform Abstract: Cycloaddition/Ring Opening of 3-Unsubstituted Cyclic Nitronates, Isoxazoline and 5,6-Dihydro-4H-1,2-oxazine N-Oxides, as Synthetic Equivalents of Functionalized Nitrile Oxides.

✍ Scribed by S. KANEMASA; T. YOSHIMIYA; E. WADA

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 32 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199908134

✦ Synopsis

Cycloaddition/Ring Opening of 3-Unsubstituted Cyclic Nitronates, Isoxazoline and 5,6-Dihydro-4H-1,2-oxazine N-Oxides, as Synthetic Equivalents of Functionalized Nitrile Oxides. -Treatment of 3-halo-1-nitropropane [cf. (I)] with base results in cyclization to a nitronate. Trapping with electron-rich olefins (II) results in formation of the isoxazolines (III). Their formation is believed to proceed via rearrangement of the cyclic nitronates to nitrile oxide and following 1,3-dipolar cycloaddition. Electron-deficient alkenes such as (V) yield the Michael adduct (VI) by trapping of the anion derived from the cyclic nitronate. Furthermore, basic treatment of 4-halo-1-nitrobutanes [cf. (VII)] gives the corresponding 6-membered cyclic nitronate, which readily under goes 1,3-dipolar cycloaddition with standard dipolarophiles. -(KANEMASA,