2759-52-6Relevant articles and documents
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.
Tungsten-Catalyzed Transamidation of Tertiary Alkyl Amides
Feng, Fang-Fang,Liu, Xuan-Yu,Cheung, Chi Wai,Ma, Jun-An
, p. 7070 - 7079 (2021/06/30)
Transamidation has recently emerged as a straightforward and convenient means to diversify amides. However, the kinetically and thermodynamically demanding transamidation of notoriously robust, fully alkyl-substituted tertiary amides still remains a longstanding challenge. Here, we describe a method for the activation of tertiary alkyl amides to streamline transamidation using simple tungsten(VI) chloride as a catalyst and chlorotrimethylsilane as an additive. The highly electrophilic and oxophilic tungsten catalyst enables the selective scission of a C-N bond of tertiary alkyl amides to effect transamidation of a myriad of structurally and electronically diverse tertiary alkyl amides and amines. Mechanistic study implies that the synergistic effect of the catalyst and the additive could pronouncedly induce the nucleophilic acyl substitution of tertiary alkyl amide with amine to realize transamidation.
Dehydrative Beckmann rearrangement and the following cascade reactions
Liu, Yinghui,Wei, Yongjiao,Xie, Lan-Gui
supporting information, (2021/11/16)
The Beckmann rearrangement has been predominantly studied for the synthesis of amide and lactam. By strategically using the in situ generated Appel's salt or Mitsunobu's zwitterionic adduct as the dehydrating agent, a series of Beckmann rearrangement and following cascade reactions have been developed herein. The protocol allows the conversion of various ketoximes into amide, thioamide, tetrazole and imide products in modular procedures. The generality and tolerance of functionalities of this method have been demonstrated.
