Methyl 2-chloro-2-cyclopropylideneacetate (2) and its spiropentane analogue 3 cycloadd to dihydroisoquinoline N-oxide (9), pyrroline N-oxide (12), and C-phenyl-N-methylnitrone (16) to give 5-spirocyclopropaneisoxazolidines in good yields (58-93%). The thermal behavior of the 5-spirocyclopropaneisoxazolidines is rather differentiated, depending strongly on the constitution of the nitrone and the solvent. As nitrone 9 has the tendency to undergo cycloreversion reactions, the ketoamide rearrangement products 20 and 21 from its cycloadduct derive from the thermodynamically favored 4-spirocyclopropaneisoxazolidine regioisomers formed after the cycloreversion process.
View Article and Find Full Text PDFEpoxidation of triquinacene 3 with dimethyldioxirane proceeded with a high degree of exo-face selectivity to give a quantitative yield of a 1:1.5 mixture of all-exo-4a and endo,exo,exo-triepoxytriquinane 4b. Subsequent lithium aluminum hydride reduction of the all-exo-triepoxide 4a gave all-exo-2,5,8-5a and all-exo-2,5,9-trihydroxytriquinane 5b, respectively.
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