TRIMETHYLSILYL TRIFLUOROMETHANESULFONATE-PROMOTED CYCLOADDITION OF NITRONES WITH SILYL ENOL ETHERS - SYNTHESIS AND REACTIVITY OF 5-SILOXYISOXAZOLIDINES

In the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf), the reaction of nitrones with silyl enol ethers affords 5-siloxyisoxaz olidines under mild conditions, in good to excellent yields. 5-Siloxyi soxazolidines can undergo chemoselective reductions to Mannich bases o r N-hydroxy-1,3-amino alcohols, and, in the presence of TMSOTf, react with silylated carbon nucleophiles at the acetalic C-5 carbon to give, for example, 5-allyl- and 5-cyano-isoxazolidines.