Base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamine derivatives
The base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamines giving α-(2-hydroxyphenyl)amides was successfully demonstrated. The substrates were prepared from N-substituted hydroxylamines by N-acylation followed by copper(I)-mediated O-arylation with boronic acids. Treatment of the substrates with lithium hexamethyldisilazide (LiHMDS) in THF at 0 °C to room temperature generated the corresponding amide enolates. The aromatic [3,3] rearrangement of the enolates provided the desired products in moderate to good yields. A crossover experiment produced only intramolecular products and clarified that the reaction proceeds via the aromatic [3,3] sigmatropic rearrangement, not a bond-cleavage–recombination process. Our method is a formal α-arylation of amides.
Tayama, Eiji,Hirano, Kazuki
p. 665 - 673
(2019/01/04)
Visible-Light-Mediated Synthesis of Amidyl Radicals: Transition-Metal-Free Hydroamination and N-Arylation Reactions
The development of photoredox reactions of aryloxy-amides for the generation of amidyl radicals and their use in hydroamination-cyclization and N-arylation reactions is reported. Owing to the ease of single-electron-transfer reduction of the aryloxy-amides, the organic dye eosin Y was used as the photoredox catalyst, which results in fully transition-metal-free processes. These transformations exhibit a broad scope, are tolerant to several important functionalities, and have been used in the late-stage modification of complex and high-value N-containing molecules.
Davies, Jacob,Svejstrup, Thomas D.,Fernandez Reina, Daniel,Sheikh, Nadeem S.,Leonori, Daniele
p. 8092 - 8095
(2016/07/16)
Rhodium(III)-catalyzed C-H olefination for the Synthesis of ortho-alkenyl phenols using an oxidizing directing group
By using an oxidizing directing group, a mild, efficient Rh(III) catalyzed C-H olefination reaction between N-phenoxyacetamides and alkenes was developed. This reaction provided a straightforward way for the synthesis of ortho-alkenyl phenols, and the directing group is traceless in the product.
Shen, Yangyang,Liu, Guixia,Zhou, Zhi,Lu, Xiyan
p. 3366 - 3369
(2013/07/26)
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