Striking AcOH Acceleration in Direct Intramolecular Allylic Amination Reactions
作者:Fady Nahra、Frédéric Liron、Guillaume Prestat、Carlo Mealli、Abdelatif Messaoudi、Giovanni Poli
DOI:10.1002/chem.200901946
日期:2009.10.26
An acid–base reaction to speed up a sluggish catalytic cycle! AcOH as the solvent enables extraordinarily fast and efficient PdII‐catalysed, directintramolecularallylicaminations, assisting the benzoquinone‐mediated palladium reoxidation and ionisation of the intermediate palladium complexes (see scheme). The structural and energetic aspects of such a key step of the catalytic cycle are illustrated
Diversification of a β-lactam pharmacophore via allylic C–H amination: accelerating effect of Lewis acid co-catalyst
作者:Xiangbing (Ben) Qi、Grant T. Rice、Manjinder S. Lall、Mark S. Plummer、M. Christina White
DOI:10.1016/j.tet.2010.04.064
日期:2010.6
This report describes the use of Pd(II)/bis-sulfoxide 1 catalyzed intra- and intermolecular allylic C-H amination reactions to rapidly diversify structures containing a sensitive beta-lactam core similar to that found in the monobactam antibiotic Aztreonam. Pharmacologically interesting oxazolidinone, oxazinanone, and linear amine motifs are rapidly installed with predictable and high selectivities under conditions that use limiting amounts of substrate. Additionally, we demonstrate for the first time that intramolecular C-H amination processes may be accelerated using catalytic amounts of a Lewis acid co-catalyst [Cr(III)(salen)Cl 2]. (C) 2010 Elsevier Ltd. All rights reserved.
Allylic C−H Amination for the Preparation of <i>syn</i>-1,3-Amino Alcohol Motifs
作者:Grant T. Rice、M. Christina White
DOI:10.1021/ja9054959
日期:2009.8.26
A highly selective and general Pd/sulfoxide-catalyzed allylic C-H amination reaction en route to syn-1,3-amino alcohol motifs is reported. Key to achieving this reactivity under mild conditions is the use of electron-deficient N-nosyl carbamate nucleophiles that are thought to promote functionalization by furnishing higher concentrations of anionic species in situ. The reaction is shown to be orthogonal to classical C-C bond-forming/-reduction sequences as well as nitrene-based C-H amination methods.
Synthesis of <i>anti-</i>1,3 Amino Alcohol Motifs via Pd(II)/SOX Catalysis with the Capacity for Stereodivergence
作者:Rulin Ma、Jonathon Young、Rossella Promontorio、Friederike M. Dannheim、Christopher C. Pattillo、M. Christina White
DOI:10.1021/jacs.9b02690
日期:2019.6.19
substrates, avg. 66% isolated yield, >20:1 dr) and high selectivities (avg. 10:1 dr). Switching ligands to (±)-CF3-SOX with the use of a less bulky quinone oxidant, the kinetic syn-1,3 amino alcohol motif can be accessed in comparable yields and selectivities. Advantages of the stereodivergent nature of this reaction are seen in the synthesis of anti- and syn-1,3 amino alcohol vitamin D3 analogue intermediates