3-Bromo-propenyl acetate in organic synthesis: an expeditious route to 3-alkyl-4-acetoxy-5-iodomethyl isoxazolidines

摘要

N-Trimethylsilyloxy-N-benzyl-l-alkyl-2-acetoxy-3-buten-l-amines 13,obtained in good yields and moderate diastereo-selectivities by TMSOTf promoted alpha-acetoxyallylation of nitrones using metallic zinc and 3-bromo-propenyl acetate 11,are exploited in a stereospecific 5-exo-trig iodocyclization reaction to afford 4,5-cis-3-alkyl-4-acetoxy-5-iodomethyl isoxazolidines 14,promising starting materials for the synthesis of pyrrolidine azasugars.