Categories: C=N Bond Formation >
Synthesis of oximes
In the presence of zinc oxide and without any additional organic solvents, Beckmann rearrangement of several ketones and aldehydes were performed in good yields.
H. Sharghi, M. Hosseini, Synthesis, 2002, 1057-1059.
A new synthesis of enamides from ketones involves a phosphine-mediated reductive acylation of oximes. The resulting enamides are isolated in good yields and excellent purity.
H. Zhao, C. P. Vandenbossche, S. G. Koenig, S. P. Singh, R. P. Bakale, Org. Lett., 2008, 10, 505-507.
The use of m-CPBA as an oxidant in ethyl acetate enables an efficient, rapid oxidation of various aliphatic amines to oximes in high conversion with >90% oxime selectivity at room temperature under catalyst-free conditions.
V. V. Patil, E. M. Gayakwad, G. S. Shankarling, J. Org. Chem., 2016, 81, 781-786.
J. P. Waldo, R. C. Larock, Org. Lett., 2005, 7, 5203-5205.
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 reaction of N-alkylhydroxylamines and aqueous hydroxylamine with monosubstituted allenes gives nitrones and oximes, respectively, in good yields. DFT calculations support a proposed concerted, five-membered Cope-type hydroamination process, and calculated transition state energies are in excellent agreement with experimental observations.
J. Moran, J. Y. Pfeiffer, S. I. Gorelsky, A. M. Beauchemin, Org. Lett., 2009, 11, 1895-1898.
A general, efficient, and metal-free method for aerobic oxidation of primary benzylamines to the corresponding oximes in good yields is catalyzed by N,N′,N″-trihydroxyisocyanuric acid in the presence of acetaldoxime and water as solvent. This practical method uses air as economic and green oxidant, water as green solvent, and tolerates a wide range of substrates.
J. Yu, M. Lu, Synlett, 2014, 25, 1873-1878.
A number of new reactions of IBX with heteroatom-containing substrates were discovered and their utility was demonstrated. IBX was used for the generation of imines from secondary amines in notably high yields, for the oxidative aromatization of nitrogen heterocycles and for the cleavage of dithianes.
K. C. Nicolaou, C. J. N. Mathison, T. Montagnon, Angew. Chem., 2003, 115, 4211-4216.
A convenient, environmentally friendly method for the synthesis of optically active aldoximes and nitriles starting from chiral nitroalkanes was developed.
C. Czekelius, E. M. Carreira, Angew. Chem. Int. Ed., 2005, 44, 612-615.
Syntheses of oximes either provide mixtures of E and Z isomers or the thermodynamically preferred E isomer. Photoisomerization of aryl oximes via visible-light-mediated energy transfer (EnT) catalysis enables a mild and general method to achieve Z isomers. In a one-pot protocol for oxime isomerization and subsequent Beckmann rearrangement, alkyl groups migrate preferentially over aryl groups.
X. Zhang, T. Rovis, J. Am. Chem. Soc., 2021, 143, 21211-21217.