Asymmetric syntheses of the naturally occurring β-amino acids, β-lysine, β-leucine and β-phenyl-β-alanine via nitrone cycloaddition

Asymmetric synthesis of enantiopure isoxazolidinone monomers for the synthesis of β3-oligopeptides by chemoselective amide ligation

“…The most attractive, from asynthetic point of view, was the use of commercially available substituted acrylonitriles 19 or 20 22,23. Indeed, the combination of d -gulose derived hydroxylamine 1 , an aldehyde, and either of these acrylates afforded cycloadducts 21 or 22 in respectable yield.…”

Selectivity in 1,3‐Dipolar Cycloadditions of β‐Substituted Captodative Olefins – An Experimental and DFT Transition State Study

“…However, the 1,3‐dipolar additions of nitrones to 1,2‐disubstituted olefins bearing carbonyl and methyl groups with the ( E ) geometry, such as olefins 12 , yield only the C‐4 regioisomer 17. Other captodative olefins,17,18 and most dipolarophiles monosubstituted with either electron‐donating or electron‐withdrawing groups add to nitrones18f,19 to yield the C‐5 orientation, preferentially.…”

A Convenient Synthetic Route towards 3,5‐Bis(hydroxymethyl)pyrrolizidines: Stereoselective Synthesis of Unnatural (–)‐Hyacinthacine B2

“…Acetoxyisoxazolidine 15 was prepared, as previously described, from known D‐mannose‐derived nitrone 5 by the syn ‐stereoselective 1,3‐dipolar cycloaddition with vinyl acetate (neat, 75 °C, 24 h) in 72% yield . Its hydrolysis according to Moffat's method with potassium carbonate in aqueous methanol gave isoxazolidinol 10 (Scheme ) in almost quantitative 96% isolated yield as a mixture two undefined anomers in a 65:35 ratio.…”