Nitrone 1 + 3 cycloaddition

Cycloadditions Nitrone- and Electron-deficient Olefin-based Reactions... [Pg.262]

Cycloadditions Diels-Alder reactions [8.1] [3+2]-Cycloadditions Nitrone-based reactions [8.2]... [Pg.416]

Dipolar cycloadditions. Nitrones such as 1 combine with alkenes to form isoxazolidines. Tufariello has employed these 1,3-dipolar cycloadditionS as key steps in the synthesis of several alkaloids. Monosubstituted olefins react with nitrones regioselectively to afford 5-substituted iSoxazolidines thus addition of 2 to 1-pyrroline-l-oxide produces the cycioadduct 3, which serves as an intermediate in a total synthesis of elaeocarpine (4). ... [Pg.507]

The cycloadditions of nitrones with activated acetylenes provide 4-oxa-zolines, which readily ring open into highly stabilized azomethine ylides (Section II,H). This concept can be utilized in an intramolecular cycloaddition. Nitrones 277 undergo cycloadditions with dimethyl acetylenedi-carboxylate (OMAD) to give cycloadducts 278 through the formation of intermediary azomethine ylides (84CL797). It is quite surprising that the... [Pg.334]

Cycloaddition. Through empirical screening the dinuclear Ti complex 4 of 6,6 -diiodo-BINOL and the complex prepared from 5 have been chosen to promote 1,3-dipolar cycloaddition (nitrone -I- enal) and hetero-Diels-Alder reaction (Danishefsky s diene + RCHO), respectively. [Pg.21]

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