Generation of Nitrile Oxides from Oximes Using t-BuOI and Their Cycloaddition

Abstract

tert-Butyl hypoiodite (t-BuOI) was found to be a powerful reagent for the cycloaddition of oximes and alkenes/alkynes, leading to the formation of a variety of isoxazolines or isoxazoles under mild conditions.

DBU‐Mediated [3+2] Cycloaddition Reactions of Donor–Acceptor Cyclopropanes with Nitromethane: Efficient Strategy for the Construction of Isoxazole Skeletons

“…[28] These isoxazole-5-carboxylate derivatives have usually been obtained through traditional approaches, including the condensation of 1,3-dicarbonyl compounds with hydroxylamine, [29] the 1,3-dipolar cycloaddition of nitrile oxides with alkynes or their equivalents, [30] solid-phase methods that involve anchoring a nitrile oxide precursor onto resins, [31] and 1,3-dipolar cycloaddition reactions using 1,1-disubstituted bromoalkenes as alkyne equivalents for regioselective synthesis. Recently, it was reported that various oxidizers, such as Magtrieve™ (CrO 2 ), MnO 2 , [32] Oxone, [33] hydroxy(tosyloxy)iodobenzene (HTIB), [34] and tBuOI, [35] mediate the oxidation of aldoximes to nitrile oxides, and subsequent reactions with various dipolarophiles gave isoxazoles. These methods, however, suffered from several disadvantages, such as the limitation of substrates, harsh reaction conditions, and poor chemoselectivity.…”

Understanding the Regioselective and Molecular Mechanism of the TCE in Cycloaddtion Reaction (TCE+Cp) and Addition Reaction (TCE+HCl) using DFT calculation

“…They are also useful intermediates for synthesis of natural products and biologically active compounds [4][5][6][7][8][9][10]. A variety of synthetic methods has been developed for preparation of cyclic compounds, of which the most convenient and attractive route is probably the cycloaddition of diene or dipole to alkenes [10][11].…”

Oxidative Cycloaddition of Aldoximes with Maleimides using Catalytic Hydroxy(aryl)iodonium Species

“…[11] In the initial experiments, we investigated the oxidative cyclization of aldoximes with maleimides using stoichiometric amounts of a hypervalent iodine(III) reagent (IBA-TfOH 3). We have found that the reaction of benzaldoxime 1a (1 equiv.…”

“…Compared to the previously reported procedure of oxidative cycloaddition of aldoximes and N-phenyl-substituted maleimides using stoichiometric t-BuOI generated from the NaI-t-BuOCl combination, our catalytic procedure gives comparable or higher yields of pyrroloisoxazoles. [11] Moreover, our procedure allows us to synthesize the parent N-unsubstituted products (4a-4l), which cannot be obtained by using stochiometric t-BuOI as the oxidant. [11] The structure of one of these products, pyrrolo-isoxazole 4c, was characterized by X-ray crystallography (see the Supporting Information for details).…”

“…[11] Moreover, our procedure allows us to synthesize the parent N-unsubstituted products (4a-4l), which cannot be obtained by using stochiometric t-BuOI as the oxidant. [11] The structure of one of these products, pyrrolo-isoxazole 4c, was characterized by X-ray crystallography (see the Supporting Information for details).…”