(5S)-3-Phenyl-5-[(6R,7R,14R)-1,8,13,16-tetraoxadispiro[5.0.5.4]hexadecan-14-yl]-4,5-dihydroisoxazole: the Major Adduct Resulting from Cycloaddition of Benzonitrile Oxide to (6R,7R,14S)-14-Vinyl-1,8,13,16-tetraoxadispiro[5.0.5.4]hexadecane

This structure determination of C₂₁H₂₇NO₅, taken with the known absolute configuration of the starting alkene, establishes the configuration of the new stereogenic centre C5 in the title compound. The five-membered 4,5-dihydroisoxazole ring adopts a predominantly envelope conformation folded between O1 and C4, and the two pyranoid rings and the 1,4-dioxane ring of the dispiroketal unit are in chair conformations.

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