scholarly journals Allylic Amines as Key Building Blocks in the Synthesis of (E)-Alkene Peptide Isosteres

2012 ◽  
Vol 16 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Erin M. Skoda ◽  
Gary C. Davis ◽  
Peter Wipf
Keyword(s):  
Building Blocks ◽  
Allylic Amines ◽  
Peptide Isosteres

scholarly journals Electrochemical Synthesis of Allylic Amines from Alkenes and Amines

2021 ◽  
Author(s):  
Diana Wang ◽  
Karina Targos ◽  
Zachary Wickens
Keyword(s):  
Aliphatic Amine ◽  
Reactive Intermediates ◽  
Building Blocks ◽  
Electrochemical Process ◽  
Biologically Active ◽  
Secondary Amines ◽  
High Yield ◽  
Mechanistic Studies ◽  
Allylic Amines ◽  
Synthetic Strategy

Allylic amines are valuable synthetic targets en route to diverse biologically active amine products. Current allylic C–H amination strate-gies remain limited with respect to the viable N-substituents. Herein we disclose a new electrochemical process to prepare aliphatic allylic amines by coupling two abundant starting materials: secondary amines and unactivated alkenes. This oxidative transformation proceeds via electrochemical generation of an electrophilic adduct between thianthrene and the alkene substrates. Treatment of these adducts with aliphatic amine nucleophiles and base provides allylic amine products in high yield. This synthetic strategy is also amenable to functionali-zation of feedstock gaseous alkenes at 1 atmosphere. In the case of 1-butene, remarkable Z-selective crotylation is observed. This strategy, however, is not limited to the synthesis of simple building blocks; complex biologically active molecules are suitable as both alkene and amine coupling partners. Preliminary mechanistic studies implicate vinylthianthrenium salts as key reactive intermediates.

scholarly journals Site-Selective Allylic C-H Amination with Aliphatic Amines

2021 ◽  
Author(s):  
Shengchun Wang ◽  
Yiming Gao ◽  
Demin Ren ◽  
He Sun ◽  
Linbin Niu ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Building Blocks ◽  
Hydrogen Atom Transfer ◽  
Allylic Amines ◽  
Allylic Amination ◽  
Alkyl Amines ◽  
Reaction Proceeds ◽  
Bond Options ◽  
A Site ◽  
Site Selective

Abstract The direct coupling of olefins and alkyl amines represents the most efficient and atom-economical approach to prepare aliphatic allylamines which are fundamental building blocks. However, the method that achieves this goal while exhibiting exquisite control over the site at which the amine is introduced remains elusive. Herein, we report that the combination of a photocatalyst and a cobaloxime enables site-selective allylic C–H amination of olefins with secondary alkyl amines to afford allylic amines, eliminating the need for oxidants. This reaction proceeds by a radical-based mechanism distinct from those of existing allylic amination reactions. It affords the product resulting from cleavage of the stronger, primary allylic C–H bonds over other weaker allylic C–H bond options. DFT calculations reveal that this selectivity originates from a cobaloxime-promoted hydrogen atom transfer (HAT) process. Our method is compatible with a broad scope of alkenes, and can be extended to achieve a site- and diastereoselective amination of natural terpenes.

scholarly journals Ni-catalyzed hydroaminoalkylation of alkynes with amines

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei-Wei Yao ◽  
Ran Li ◽  
Hao Chen ◽  
Ming-Kai Chen ◽  
Yu-Xin Luan ◽  
...  
Keyword(s):  
Transition Metal ◽  
Organic Synthesis ◽  
Bioactive Compounds ◽  
Building Blocks ◽  
Late Transition Metal ◽  
Allylic Amines ◽  
Formidable Challenge ◽  
Late Transition

AbstractAllylic amines are versatile building blocks in organic synthesis and exist in bioactive compounds, but their synthesis via hydroaminoalkylation of alkynes with amines has been a formidable challenge. Here, we report a late transition metal Ni-catalyzed hydroaminoalkylation of alkynes with N-sulfonyl amines, providing a series of allylic amines in up to 94% yield. Double ligands of N-heterocyclic carbene (IPr) and tricyclohexylphosphine (PCy3) effectively promote the reaction.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

Laboratory and in-situ analysis of comet dust

1988 ◽  
Vol 46 ◽  
pp. 8-9
Author(s):  
D.E. Brownlee ◽  
A.L. Albee
Keyword(s):  
Electron Microscopy ◽  
Solar System ◽  
Laboratory Study ◽  
Isotopic Analysis ◽  
Building Blocks ◽  
Sem Analysis ◽  
Early Solar System ◽  
Cometary Material ◽  
Comet Dust

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.

Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions

1993 ◽  
Vol 51 ◽  
pp. 876-877
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Microstructural Characterization ◽  
Building Blocks ◽  
Quantitative Information ◽  
Physical Models ◽  
Specimen Preparation ◽  
Time Resolved ◽  
Temperature Changes ◽  
Temperature And Humidity ◽  
Microstructured Fluids ◽  
Air Streams

To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

Emotional Variability Predicts Tiredness in Daily Life

2016 ◽  
Vol 37 (3) ◽  
pp. 181-193 ◽  
Author(s):  
Aire Mill ◽  
Anu Realo ◽  
Jüri Allik
Keyword(s):  
Sampling Method ◽  
Daily Life ◽  
Emotional Experience ◽  
Experience Sampling ◽  
Experience Sampling Method ◽  
Building Blocks ◽  
Intraindividual Variability ◽  
Unique Role ◽  
Over Time

Abstract. Intraindividual variability, along with the more frequently studied between-person variability, has been argued to be one of the basic building blocks of emotional experience. The aim of the current study is to examine whether intraindividual variability in affect predicts tiredness in daily life. Intraindividual variability in affect was studied with the experience sampling method in a group of 110 participants (aged between 19 and 84 years) during 14 consecutive days on seven randomly determined occasions per day. The results suggest that affect variability is a stable construct over time and situations. Our findings also demonstrate that intraindividual variability in affect has a unique role in predicting increased levels of tiredness at the momentary level as well at the level of individuals.

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