The asymmetric synthesis of allylglycine and other unnatural α-amino acids via zinc-mediated allylation of oximes in aqueous media
作者:Stephen Hanessian、Rui-Yang Yang
DOI:10.1016/0040-4039(96)01118-5
日期:1996.7
Enantiomerically pure or highly enriched allylglycine and its chain-substituted analogs are easily accessible from the reaction of the sultam derivative of O-benzyl glyoxylic acidoxime with allylic bromides in the presence of powdered zinc in aqueous ammonium chloride.
1- and 2-Azetines via Visible Light-Mediated [2 + 2]-Cycloadditions of Alkynes and Oximes
作者:Emily R. Wearing、Dominique E. Blackmun、Marc R. Becker、Corinna S. Schindler
DOI:10.1021/jacs.1c07523
日期:2021.10.6
accessible upon intermolecular [2 + 2]-cycloaddition via triplet energy transfer from a commercially available iridium photocatalyst, the selective formation of 1-azetines proceeds upon a second, consecutive, energy transfer process. Mechanistic studies are consistent with a stepwise reactionmechanism via N–O bond homolysis following the second energy transfer event to result in the formation of 1-azetine products
Oximes of 5,5-disubstituted 1-azapenta-1,4-dien-3-ones 3 underwent 1,5-cyclization reactions yielding indenole derivatives 4 in moderate to good yields upon treatment with an excess of trifluoromethanesulfonic acid. Similarly, the hydrazone 3g led to indenole 4f upon protonation. The reaction could also be successfully applied to the synthesis of benzo[b]cyclopenta[d]thiophene 5 starting from 3f. Products of a competing aza-Nazarov reaction were not observed. The reaction mechanism is explained by assuming the involvement of dicationic intermediates, generated by superelectrophilic solvation, similar to that of known Nazarov and aza-Nazarov-type transformations. Quantum chemical calculations of reaction energies and activation barriers are discussed with respect to the experimental results.
Catalytic Cascade Access to Biaryl-2-Methyl Acetates from Pyruvate<i>O</i>-Arylmethyl Ketoximes<i>via</i>the Palladium-Catalyzed C(<i>sp</i><sup>2</sup>)H Bond Arylation and C−O Bond Solvolysis
作者:Ling-Yan Shao、Li-Hao Xing、Ying Guo、Kun-Kun Yu、Wei Wang、Hong-Wei Liu、Dao-Hua Liao、Ya-Fei Ji
DOI:10.1002/adsc.201800216
日期:2018.8.6
A catalytic cascade has been developed for the synthesis of biaryl‐2‐methyl acetates via a palladium‐catalyzed ortho‐C(sp2)−H bond arylation of pyruvate O‐arylmethyl ketoximes with aryl iodides followed by a solvolysis, in which the pyruvic ketoxime ester as a new auxiliary is employed to direct the C(sp2)−H bond activation. The straightforward treatment of O‐arylmethyl hydroxylamines and ethyl pyruvate