Base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamine derivatives
作者:Eiji Tayama、Kazuki Hirano
DOI:10.1016/j.tet.2018.12.058
日期:2019.2
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] sigmatropicrearrangement, not a bond-cleavage–recombination process. Our method is a formal α-arylation of amides.
Asymmetric synthesis using chirally modified borohydrides. Part 3. Enantioselective reduction of ketones and oxime ethers with reagents prepared from borane and chiral amino alcohols
The asymmetric reduction of aromatic and aliphatic ketones, halogeno ketones, hydroxy ketones, keto esters, and ketone oxime ethers with reagents prepared from borane and chiral amino alcohols has been investigated. When α,α-diphenyl β-amino alcohols, such as (2S,3R)-(–)-2-amino-3-methyl-1,1 -diphenylpentanol (2d), were used as a chiral auxiliary, very high enantioselectivities (ca. 90 % e.e.) were
Thermal decomposition of O-benzyl ketoximes; role of reverse radical disproportionation
作者:Jessie A. Blake、Keith U. Ingold、Shuqiong Lin、Peter Mulder、Derek A. Pratt、Brad Sheeller、John C. Walton
DOI:10.1039/b313491a
日期:——
9,10-dihydrophenanthrene and 9,10-dihydroanthracene than in tetralin. These results indicated that a reverse radical disproportionation reaction in which a hydrogen atom was transferred from the solvent to the oxime ether, followed by [small beta]-scission of the resultant aminoalkyl radical, must be important in the latter two solvents. Benzaldehyde was found to be an additional product from thermolyses
Metal-Free 2,2,6,6-Tetramethylpiperidin-1-yloxy Radical (TEMPO) Catalyzed Aerobic Oxidation of Hydroxylamines and Alkoxyamines to Oximes and Oxime Ethers
作者:Sebastian Wertz、Armido Studer
DOI:10.1002/hlca.201200175
日期:2012.10
TEMPO‐Mediatedoxidation of hydroxylamines (=hydroxyamines) and alkoxyamines to the corresponding oxime derivatives is reported (TEMPO=2,2,6,6‐tetramethylpiperidin‐1‐yloxy radical; Scheme 2). These environmentally benign oxidations proceed in good to excellent yields (Table 1). For alkoxyamines, oxidation to the corresponding oxime ethers can be performed by using dioxygen as a terminal oxidant in
A removable oxime-assisted meta-C–H nitration of arenes is reported. Mechanistic investigations and DFT calculations reveal a new monomeric octahedral ruthenium(II) complex is responsible for the meta-selective nitration. Dioxygen as a cooxidant is crucial for achieving high conversion and good yields. Moreover, the utility of the present reaction protocol is further showcased by the late-stage modification