A complementary method to obtain N-acyl enamides using the Heck reaction: extending the substrate scope for asymmetric hydrogenation
摘要:
A method to prepare N-acyl enamides is reported that is complementary to the existing protocols. Heck reaction of a variety of aryl trifluoromethanesulfonates with commercially available N-vinylacetamide occurred in a highly regioselective fashion to provide these valuable synthetic intermediates. This method permits the formation of N-acyl enamides containing functionality that would not be tolerated by the existing methods. Asymmetric hydrogenation using [diphosphine RhCOD]BF4 complexes provided optically active protected amines in up to 99% ee. De-acylation occurs without affecting the amine enantiopurity. (C) 2004 Elsevier Ltd. All rights reserved.
Direct Enamido C(sp<sup>2</sup>)−H Diphosphorylation Enabled by a PCET‐Triggered Double Radical Relay: Access to<i>gem</i>‐Bisphosphonates
作者:Hao‐Qiang Cao、Hao‐Nan Liu、Zhe‐Yuan Liu、Bao‐Kun Qiao、Fa‐Guang Zhang、Jun‐An Ma
DOI:10.1002/chem.202000517
日期:2020.4.24
electron-transfer (PCET)-triggered enamidoC(sp2 )-Hdiphosphorylation. This reaction represents a rare example of realizing the challenging double C-P bond formation at a single carbon atom, thus providing facile access to a broad variety of structurally diverse bisphosphonates from simple enamides under silver-mediated conditions. Initial mechanistic studies demonstrated that the diphosphorylation involves
Direct Titanium-Mediated Conversion of Ketones into Enamides with Ammonia and Acetic Anhydride
作者:Jonathan T. Reeves、Zhulin Tan、Zhengxu S. Han、Guisheng Li、Yongda Zhang、Yibo Xu、Diana C. Reeves、Nina C. Gonnella、Shengli Ma、Heewon Lee、Bruce Z. Lu、Chris H. Senanayake
DOI:10.1002/anie.201107601
日期:2012.2.6
A one‐step conversion of ketones into N‐acetyl enamides was developed. The process employs safe and inexpensive reagents, proceeds under mild conditions, and tolerates diverse functional groups. The addition of edte (N,N,N′,N′‐tetrakis(2‐hydroxyethyl)ethylenediamine) prior to workup enables water solubilization of Ti alkoxides and allows a simple extractive workup.
Hydrogen peroxide and anhydride mediated transformation of enamides to afford substituted α-acyloxy ketones is described. This transition-metal-free cascade reaction has a broad substrate scope and high efficiency. The acyl intramolecular migration procedure successfully achieved this acyloxylation process under mild conditions and increased the atom efficiency.
Combinatorial Strategies to find New Catalysts for Asymmetric Hydrogenation Based on the Versatile Coordination Chemistry of METAMORPhos Ligands
作者:Frédéric G. Terrade、Alexander M. Kluwer、Remko J. Detz、Zohar Abiri、Alida M. van der Burg、Joost N. H. Reek
DOI:10.1002/cctc.201500621
日期:2015.10
both the anionic and neutral ligands have the same chirality. If the neutral ligand and the anionicligand have the opposite chirality at the P atom, monometallic and bimetallic heterocomplexes were detected by NMR spectroscopy and MS. For the majority of substrates evaluated in this study, higher enantioselectivities were obtained if the complexes used were based on the heterocombination of an anionic
Chiral β-Keto Propargylamine Synthesis via Enantioselective Mannich Reaction of Enamides with <i>C</i>-Alkynyl <i>N</i>-Boc <i>N</i>,<i>O</i>-Acetals
作者:Fang-Fang Feng、Shen Li、Chi Wai Cheung、Jun-An Ma
DOI:10.1021/acs.orglett.9b03181
日期:2019.10.18
Propargylamines are an important class of compounds in organic synthesis and drug discovery, yet the synthesis of chiral β-keto propargylamines remains underdeveloped. Herein, we describe a streamlined and general enantioselective Mannichreaction of enamides with C-alkynyl N-Boc N,O-acetals, which serve as readily available C-alkynyl imine precursors, to access a broad range of chiral β-keto N-Boc-propargylamines