Hobartine

Intramolecular cycloaddition of jV-(cycloalkenyl)nitrones has also been extensively investigated. Thus, stepwise oxidation of the amine (35) and cyclization of the ensuing nitrone provided isoxazolidine (36) in 64% overall yield as the only observed regioisomer (Scheme 8).16 Isoxazolidine (36) was then desul-fonated with buffered sodium amalgam and further reduced with zinc-acetic acid to provide the corresponding y-amino alcohol subsequent dehydration provided (-)-hobartine. 

Sorelline and hobartine are two new alkaloids of A. peduncularis (Labill.) Hook. f. which were isolated by chromatography after removal of the major alkaloid, peduncularine.50 Both alkaloids, whose structures were elucidated... 

This mercuration reaction has been adapted by Stevens and Kenneyto perform elegant stereospe-cific syntheses of the Aristotelia indole alkaloids (+)-makomakine (97) and (+)-aristoteline (98) from (—)-3-pinene and indol-3-ylacetonitrile (96) in only two and three steps, respectively (Scheme 51). A similar procedure from (+)-a-pinene yielded racemic hobartine (99) in 11% overall yield. Enantiospecificity is not observed in this reaction for the same reasons encountered during the preparations of (93) and (94). 94... 

Peduncularine, isopeduncularine, aristoserratine, hobartine, sorelline, tasmanine... 

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