A Facile Synthesis of α-Amino Esters via Reduction of α-Nitro Esters Using Ammonium Formate as a Catalytic Hydrogen Transfer Agent
作者:Siya Ram、Richard E. Ehrenkaufer
DOI:10.1055/s-1986-31497
日期:——
Various nitroesters 3 were selectively and rapidly reduced to their corresponding amino esters 4 in very good yield using anhydrous ammonium formate as a catalytic hydrogen transfer agent.
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
phase‐transfer reaction system can be applied to highly enantioselectiveconjugateaddition and aldol reactions under the influence of chiral bifunctional ammonium bromides as key catalysts. The structure of the chiral ammonium enolate intermediate is discussed based on the single‐crystal X‐ray structures of relevant ammonium salts and the importance of bifunctional design of catalyst is clearly explained in the
Diastereo- and enantioselective conjugate addition of α-substituted nitroacetates to maleimides under base-free neutral phase-transfer conditions
作者:Seiji Shirakawa、Shogo J. Terao、Rongjun He、Keiji Maruoka
DOI:10.1039/c1cc14043d
日期:——
Highly diastereo- and enantioselective conjugate addition of alpha-substituted nitroacetates to maleimides under base-free neutral phase-transfer conditions was developed for the synthesis of alpha,alpha-disubstituted alpha-amino acid derivatives.