Synthesis of stable isoxazolines by [3+2] cycloaddition of oxaziridines with alkynes

[3+2] Cycloaddition reaction between aliphatic alkynes and oxaziridines

“…7,8,9,10 Moreover, it has been reported that oxaziridines undergo a cycloaddition reaction with a variety of heterocumulenes to afford a different set of five-membered heterocycles. 7,8,9,10,11 We have recently described a simple and highly efficient [3+2] cycloaddition reaction between a variety of aryl alkenes 12 or alkynes 13 and 2-alkyl-3-aryloxaziridines. This new behaviour led to 2-alkyl-3,5-diarylisoxazolidines and 2-alkyl-3,5-diarylisoxazolines, respectively, as shown in Scheme 1.…”

A Dual Gold‐Iron Catalysis for a One‐Pot Synthesis of 2,3‐Dihydroisoxazoles from Propargylic Alcohols and N‐Protected Hydroxylamines

“…[2] Although their efficacy in both chemistry and biology has been well established, only a few methods to obtain such scaffolds have been described so far. Among the most popular of these, the [3 + 2] cycloadditions between nitrones and alkynes, [3] oxaziridine ring opening, [4] and cyclization of propargylic N-hydroxylamine [5] are worthy of note. To the best of our knowledge, these approaches appear to be restricted to N-alkyl-or Nbenzyl 2,3-dihydroisoxazoles, and so far no convenient method to obtain N-carbamate-or N-sulfonylprotected derivatives has been described.…”

The chemistry of 2,3-dihydroisoxazole derivatives

“…27 The re action is believed 27 to involve no isomerization of oxaziri dines into nitrones followed by their 1,3 dipolar cycload dition. The argument put forward is that cycloaddition of nitrones to alkynes is not regioselective, 28 while the trans formation in question yields only a 5 substituted regioiso mer of cycloadduct 18.…”