(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 C5 centre in the title compound. The five-membered 4,5-dihydroisoxazole ring adopts a predominantly envelope conformation folded between the O1 and C4 atoms, and the two pyranoid rings and the 1,4-dioxane ring of the dispiroketal unit are in chair conformations.