A tandem oximation-cyclization route to Δ-isoxazolines

3,5-Disubstituted Δ²-isoxazolines can be prepared from the corresponding β,γ-unsaturated ketones by treatment with hydroxylamine hydrochloride and sodium hydroxide. Evidence indicates that the mechanism of this reaction involves the formation of three intermediates; oximation of the ketone, rearrangement of the alkene, and intramolecular Michael addition of the resulting α,β-unsaturated oxime.     

Azomethine ylides from tin-substituted cyclic carbinol amides: a new route to highly substituted pyrrolizidines

[reaction: see text] Addition of organolithium and organomagnesium reagents to N-(tri-n-butylstannylmethyl)phthalimides yields N-(tri-n-butylstannylmethyl) cyclic carbinol amides, which form azomethine ylides upon treatment with HF.pyridine. This novel route to azomethine ylides allows rapid access to highly functionalized pyrrolizidines (1,2,3,9b-tetrahydropyrrolo[2,1-a]isoindol-5-ones).     

Storage and processing of estuarine water samples for trace metal analysis by atomic absorption spectrometry

Saline water samples from the Delaware Bay estuary were sampled, processed, and stored in a variety of ways to allow different methods of maintaining their integrity to be compared. Samples were processed onboard ship, immediately after collection, by extraction with ammonium pyrollidinedithiocarbamate in methyl isobutyl ketone. Duplicate samples were processed onshore after a variety of storage procedures. All samples were analyzed for copper and iron by atomic absorption spectrometry. Only samples filtered (<1 μm), acidified, and stored frozen gave extractable copper and iron results comparable with those for samples extracted immediately after collection. Cold storage with sample acidification in polyethylene containers appeared less satisfactory. Organic extracts from samples processed onboard are best retained in all-Teflon containers pending complete digestion and analysis onshore. Unless clean (ultra-filtered air) conditions can be ensured onboard, the estuarine water samples are best returned in a filtered, acidified, and frozen condition for onshore processing.