Synthesis of hydroxylamines
With a simple two-step procedure involving substitution with readily available TsNHOTBS and subsequent treatment with CsF, a range of oximes were prepared from the corresponding alcohols, alkyl halides, or alkyl sulfonates without using external oxidants.
K. Kitahara, T. Toma, J. Shimokawa, T. Fukuyama, Org. Lett., 2008, 10, 2259-2261.
The utilization of unprotected NH2OH, which is not only an oxygen nucleophile but also a nitrogen nucleophile, in iridium-catalyzed allylic substitution provides N-(1-allyl)hydroxylamines in good to high yields with high level of chemoselectivities, regioselectivities, and enantioselectivities under mild, carefully adjusted reaction conditions.
J. Chen, Q. Liang, X. Zhao, Org. Lett., 2019, 21, 5383-5386.
The bis-pyrazole phosphine BippyPhos is an effective ligand for a smooth palladium-catalyzed cross-coupling of hydroxylamines with aryl bromides, chlorides, and iodides at 80°C in toluene in the presence of Cs2CO3 to give synthetically versatile N-arylhydroxylamine products in good to excellent yield.
A. Porzelle, M. D. Woodrow, N. C. O. Tomkinson, Org. Lett., 2009, 11, 233-236.
An efficient method for the copper-catalyzed N-arylation of hydroxylamines with aryl iodides allows the conversion of various N- and O-functionalized hydroxylamines in good to excellent yield with a broad range of aryl coupling partners. Methods for the selective deprotection of either the N- or O-substituents for further functionalization are also described.
K. L. Jones, A. Porzelle, A. Hall, M. D. Woodrow, N. C. O. Tomkinson, Org. Lett., 2008, 10, 797-800.
A highly regio- and enantioselective hydroxyamination of aldehydes with in situ generated nitrosocarbonyl compounds from hydroxamic acid derivatives was realized by combining TEMPO and BPO as oxidants in the presence of a binaphthyl-modified amine catalyst.
T. Kano, F. Shirozu, K. Maruoka, J. Am. Chem. Soc., 2013, 135, 17735-17738.
Highly regioselective ring opening of epoxides with poor nucleophiles such as indole, borane, O-trimethylsilylhydroxylamine, p-nitroaniline and sterically hindered tert-butylamine is a fast and convenient reaction in the presence of 5.0 M lithium perchlorate-Et2O solution (LPDE).
A. Heydari, M. Mehrdad, A. Maleki, N. Ahmadi, Synthesis, 2004, 1557-1558.