37899-61-9Relevant academic research and scientific papers
Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
Zhang, Xiao,Rovis, Tomislav
supporting information, p. 21211 - 21217 (2021/12/27)
Oximes are valuable synthetic intermediates for the preparation of a variety of functional groups. To date, the stereoselective synthesis of oximes remains a major challenge, as most current synthetic methods either provide mixtures of E and Z isomers or furnish the thermodynamically preferred E isomer. Herein we report a mild and general method to achieve Z isomers of aryl oximes by photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmann rearrangement that enables novel reactivity with alkyl groups migrating preferentially over aryl groups, reversing the regioselectivity of the traditional Beckmann reaction. Chemodivergent N- or O- cyclizations of alkenyl oximes are also demonstrated, leading to nitrones or cyclic oxime ethers, respectively.
Selectfluor-Bu4NI-Mediated C(sp3)-H Oxidation in Aqueous Media: Synthesis of Δ2-Isoxazolines from Oximes
Shi, Di,Qin, Hai-Tao,Zhu, Chen,Liu, Feng
supporting information, p. 5084 - 5088 (2015/08/18)
The direct functionalization of an aliphatic C-H bond within a complex molecule through a free-radical pathway is a valuable tool in synthetic chemistry. Herein, we developed an efficient transition-metal-free approach to generate Δ2-isoxazolines from oximes by radical-mediated C(sp3)-H oxidation. Investigation of the mechanism suggested that in the presence of Selectfluor and Bu4NI, the homolysis of the in situ formed O-I bond generated an iminoxyl radical that facilitated subsequent 1,5-H transfer and C(sp3)-H oxidation. The title reaction involves Selectfluor-Bu4NI-mediated C-O bond formation in aqueous media under metal-free conditions. A variety of Δ2-isoxazolines are directly synthesized from oximes by remote intramolecular functionalization of C(sp3)-H bonds.
