Preparation of useful building blocks, α-iodo- and bromoalkanols from cyclic ethers using the Dowex H+/NaX (X = I, Br) approach

RSC Advances ◽  
2016 ◽  
Vol 6 (19) ◽  
pp. 15937-15940 ◽  
Author(s):  
Petri A. Turhanen ◽  
Jouko J. Vepsäläinen
Keyword(s):  
Building Blocks ◽  
Cyclic Ethers ◽  
Synthetic Chemistry ◽  
Complex Molecules ◽  
Novel Method

Novel method for preparation of α-iodo- and bromoalkanols directly from cyclic ethers has been developed. Prepared compounds are highly important building blocks in synthetic chemistry for the preparation of more complex molecules.

scholarly journals A novel approach to the computation of one-loop three- and four-point functions: I. The real mass case

2019 ◽  
Vol 2019 (11) ◽  
Author(s):  
J Ph Guillet ◽  
E Pilon ◽  
Y Shimizu ◽  
M S Zidi
Keyword(s):  
Building Blocks ◽  
The Real ◽  
Alternative Method ◽  
Novel Approach ◽  
Reduction Methods ◽  
Real Mass ◽  
Novel Method ◽  
Algebraic Reduction ◽  
The One ◽  
Mass Case

Abstract This article is the first of a series of three presenting an alternative method of computing the one-loop scalar integrals. This novel method enjoys a couple of interesting features as compared with the method closely following ’t Hooft and Veltman adopted previously. It directly proceeds in terms of the quantities driving algebraic reduction methods. It applies to the three-point functions and, in a similar way, to the four-point functions. It also extends to complex masses without much complication. Lastly, it extends to kinematics more general than that of the physical, e.g., collider processes relevant at one loop. This last feature may be useful when considering the application of this method beyond one loop using generalized one-loop integrals as building blocks.

scholarly journals Design of True Random Number Circuit with Controllable Frequency

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1517
Author(s):  
Xinsheng Wang ◽  
Xiyue Wang
Keyword(s):  
Random Number ◽  
Noise Source ◽  
State Of The Art ◽  
Building Blocks ◽  
Encryption Algorithm ◽  
Random Numbers ◽  
Random Number Generators ◽  
Random Telegraph Noise ◽  
Telegraph Noise ◽  
Novel Method

True random number generators (TRNGs) have been a research hotspot due to secure encryption algorithm requirements. Therefore, such circuits are necessary building blocks in state-of-the-art security controllers. In this paper, a TRNG based on random telegraph noise (RTN) with a controllable rate is proposed. A novel method of noise array circuits is presented, which consists of digital decoder circuits and RTN noise circuits. The frequency of generating random numbers is controlled by the speed of selecting different gating signals. The results of simulation show that the array circuits consist of 64 noise source circuits that can generate random numbers by a frequency from 1 kHz to 16 kHz.

scholarly journals Thioesters Provide a Robust Path to Prebiotic Peptides

2021 ◽  
Author(s):  
Moran Frenkel-Pinter ◽  
Marcos Bouza ◽  
Facundo M. Fernández ◽  
Luke J. Leman ◽  
Loren Dean Williams ◽  
...  
Keyword(s):  
Building Blocks ◽  
Peptide Bond ◽  
Side Reactions ◽  
Peptide Bond Formation ◽  
One Pot ◽  
Complex Molecules ◽  
Peptide Formation ◽  
Wide Range ◽  
Amide Exchange ◽  
Prebiotic Earth

The condensation of building blocks into oligomers and polymers was an early and important stage in the origins of life. High activation energies, unfavorable thermodynamics and side reactions are bottlenecks for abiotic formation of peptides. Thioesters are hypothesized to have played key roles in prebiotic chemistry on early Earth, serving as energy storing molecules, as synthetic intermediates, and as catalysts in the formation of more complex molecules, including polypeptides. However, all abiotic reactions reported thus far for peptide formation via thioester intermediates have relied on activated building blocks or condensing agents, which are of questionable prebiotic relevance. We report robust, plausible prebiotic reactions of mercaptoacids with amino acids that result in the formation of peptides and thiodepsipeptides, which contain both peptide and thioester bonds. Peptide bond formation proceeds by the condensation of mercaptoacids to form thioesters followed by thioester-amide exchange. Mercaptoacids catalyze thiodepsipeptides and peptide formation under a wide range of pH conditions and at mild temperatures. Our results offer the most robust one-pot pathway for peptide formation ever reported. These results support the hypothesis that thiodepsipeptides formed robustly on prebiotic Earth and were possible contributors to early chemical evolution.

Enantioselective Intermolecular Murai-Type Alkene Hydroarylation Reactions

Synthesis ◽  
2021 ◽  
Author(s):  
John F. Bower ◽  
Timothy P. Aldhous ◽  
Raymond W. M. Chung ◽  
Andrew G. Dalling
Keyword(s):  
Building Blocks ◽  
Short Review ◽  
Synthetic Chemistry ◽  
Complex Building

AbstractStrategies that enable the efficient assembly of complex building blocks from feedstock chemicals are of paramount importance to synthetic chemistry. Building upon the pioneering work of Murai and co-workers in 1993, C–H-activation-based enantioselective hydroarylations of alkenes offer a particularly promising framework for the step- and atom-economical installation of benzylic stereocenters. This short review presents recent intermolecular enantioselective Murai-type alkene hydroarylation methodologies and the mechanisms by which they proceed.1 Introduction2 Enantioselective Hydroarylation Reactions of Strained Bicyclic Alkenes3 Enantioselective Hydroarylation Reactions of Electron-Rich Acyclic Alkenes4 Enantioselective Hydroarylation Reactions of Electron-Poor Acyclic Alkenes5 Enantioselective Hydroarylation Reactions of Minimally Polarized Acyclic Alkenes6 Conclusion and Outlook

scholarly journals Telescope Observations of Interstellar and Circumstellar Ices: Successes of and Need for Laboratory Simulations

2015 ◽  
Vol 11 (A29A) ◽  
pp. 317-318
Author(s):  
A. C. A. Boogert
Keyword(s):  
Thermal Processing ◽  
Protoplanetary Disks ◽  
Building Blocks ◽  
Reaction Rates ◽  
Young Stars ◽  
Complex Molecules ◽  
Laboratory Simulations ◽  
James Webb Space Telescope ◽  
History Of ◽  
Grain Surface

AbstractIces play a key role in the formation of simple and complex molecules in dense molecular clouds and in the envelopes and protoplanetary disks surrounding young stars. Some fraction of the interstellar ices may become building blocks of comets, and thus be delivered to the early Earth. Laboratory simulations have proven to be crucial in the derivation of ice abundances, in quantifying reaction rates on cold grain surfaces, in determining the thermal and energetic processing history of the ices, and in understanding the interaction between the ices and the underlying refractory grain surfaces. In this invited topical paper I will review possible ways forward in improving our knowledge of the composition of the ices, as many signatures in the interstellar spectra are still poorly identified. I will also emphasize the observed importance of thermal processing of the ices (crystallization, segregation), which likely affects the chemistry after the initial dominance of grain surface reactions. Continued laboratory work is warranted in view of the upcoming observational data from, for example, the James Webb Space Telescope (JWST), which is ideally suited for ices studies. For an exhaustive review on this topic I refer to Boogert, Gerakines & Whittet (2015).

scholarly journals Design and synthesis of a bis-macrocyclic host and guests as building blocks for small molecular knots

2020 ◽  
Vol 16 ◽  
pp. 2314-2321
Author(s):  
Elizabeth A Margolis ◽  
Rebecca J Keyes ◽  
Stephen D Lockey ◽  
Edward E Fenlon
Keyword(s):  
Molecular Weight ◽  
Electrostatic Interactions ◽  
Second Generation ◽  
Building Blocks ◽  
Design And Synthesis ◽  
Host Compound ◽  
Novel Method ◽  
Trefoil Knots

The thread–link–cut (TLC) approach has previously shown promise as a novel method to synthesize molecular knots. The modular second-generation approach to small trefoil knots described herein involves electrostatic interactions between an electron-rich bis-macrocyclic host compound and electron-deficient guests in the threading step. The bis-macrocyclic host was synthesized in eight steps and 6.6% overall yield. Ammonium and pyridinium guests were synthesized in 4–5 steps. The TLC knot-forming sequence was carried out and produced a product with the expected molecular weight, but, unfortunately, further characterization did not produce conclusive results regarding the topology of the product.

Binding to semiflexible polymers: a novel method to control the structures of small numbers of building blocks

Soft Matter ◽  
2014 ◽  
Vol 10 (38) ◽  
pp. 7661-7668 ◽  
Author(s):  
Dong Zhang ◽  
Linxi Zhang
Keyword(s):  
Elastic Medium ◽  
Building Blocks ◽  
Spatial Arrangement ◽  
Relative Orientation ◽  
Polymer Chains ◽  
Semiflexible Polymers ◽  
Spherical Building ◽  
Local Organization ◽  
Semiflexible Polymer ◽  
Novel Method

Semiflexible polymer chains can serve as an effective soft elastic medium to control the structures of small numbers of building blocks through three different aspects: local organization of two neighbor particles, spatial arrangement of small numbers of building blocks, and the relative orientation of neighboring non-spherical building blocks.

scholarly journals Mars Science Laboratory (MSL) and the future missions to Mars

2009 ◽  
Vol 5 (H15) ◽  
pp. 710-711
Author(s):  
Michel Cabane ◽  
Keyword(s):  
Building Blocks ◽  
Science Laboratory ◽  
Mars Science Laboratory ◽  
Complex Molecules ◽  
Early State ◽  
The Future ◽  
Molecular Indicators

AbstractAfter their formation, and for almost 0.5 Gyr, Mars and Earth evolved in the same manner. On Earth, life occured very early, around 3.6 Gy ago. Then, the hypothesis that life might have occured also on Mars, and be extinct, is not unrealistic. If this is true, then complex molecules could be present, representing an early state of life-building blocks. Missions to Mars (Viking 1-2, Phoenix) have carried instruments capable to search for molecular indicators, although up to now, no positive detection has been obtained. Future missions to Mars (MSL-NASA, Exomars-ESA) will use enhanced experiments to try to end this quest.

Photooxidative Keto-Trifluoromethylation of Styrenes by Means of an Anthraquinone-Based Organocatalyst

Synthesis ◽  
2018 ◽  
Vol 50 (16) ◽  
pp. 3161-3168 ◽  
Author(s):  
Eiji Yamaguchi ◽  
Akichika Itoh ◽  
Yuji Kamito ◽  
Kazuki Matsuo ◽  
Jun Ishihara
Keyword(s):  
Transition Metal ◽  
Building Blocks ◽  
Oxygen Atmosphere ◽  
Trifluoromethyl Ketones ◽  
Excellent Yield ◽  
Novel Method

α-Trifluoromethyl ketones are versatile building blocks for the synthesis of various trifluoromethyl-functionalized molecules. Although there are significant advantages in the development of methods toward direct transformations of styrenes into α-trifluoromethyl ketones, most procedures leading to α-trifluoromethyl ketones require heavy- or transition-metal-based complexes. Herein, a novel method is developed for the synthesis of α-trifluoromethyl ketones via anthraquinone-catalyzed photooxidative keto-trifluoromethylation of styrenes with the readily available Langlois reagent (CF3SO2Na) under an oxygen atmosphere. The reactions proceed smoothly to give the products in moderate to excellent yield with good selectivity.

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