Enantioselective Synthesis of Quaternary α-Amino Acids Enabled by the Versatility of the Phenylselenonyl Group
作者:Antonin Clemenceau、Qian Wang、Jieping Zhu
DOI:10.1002/chem.201604781
日期:2016.12.19
conjugate addition of α‐alkyl substituted α‐nitroacetates to phenyl vinyl selenone was developed. The resulting enantio‐enriched α,α‐dialkyl substituted α‐nitroacetates were subsequently converted to various cyclic and acyclic quaternary α‐amino acids, taking advantage of the rich functionalities of the resulting Michael adducts. Novel protocols allowing chemoselective reduction of phenyl selenone to
4<i>H</i>-1,2-Benzoxazines with Electron-Withdrawing Substituents on the Benzene Ring: Synthesis and Application as Potent Intermediates for Oxygen-Functionalized Aromatic Compounds
4H-1,2-benzoxazine rings functionalized with various electron-withdrawingsubstituents on the benzene ring. Furthermore, we also show that the resulting 4H-1,2-benzoxazines can be used as precursors of functionalized o-quinone methides and multisubstituted phenols. This type of heterocycle can be a potent intermediate to oxygen-fuctionalized aromatic compounds.
Synthesis of β-Substituted α-Amino Acids via Lewis Acid Promoted Enantioselective Radical Conjugate Additions
作者:Liwen He、G. S. C. Srikanth、Steven L. Castle
DOI:10.1021/jo051334f
日期:2005.9.1
Lewisacid promoted radicalconjugateadditions to β-substituted α,β-unsaturated α-nitro esters and amides were investigated. With achiral Lewisacids, there was competition between the desired radicalconjugateaddition and undesired alkene reduction mediated by Bu3SnH. Zinc Lewisacids provided the greatest amounts of addition products with both substrate classes. Studies with Bu3SnD indicated that
Synthesis of β-Substituted α-Amino Acids via Lewis Acid Promoted Radical Conjugate Additions to α,β-Unsaturated α-Nitro Esters and Amides
作者:G. S. C. Srikanth、Steven L. Castle
DOI:10.1021/ol036461h
日期:2004.2.1
[reaction: see text] Beta-substituted alpha,beta-unsaturated alpha-nitro esters and amides undergo radical conjugate additions when treated with an appropriate Lewis acid. Deuterium studies revealed that the acidic alpha-stereocenter of the alpha-nitro ester products does not racemize under strictly controlled workup conditions. The alpha-nitro amides did racemize significantly during chromatography