scholarly journals Lactones in the Synthesis of Prostaglandins and Prostaglandin Analogs

2021 ◽  
Vol 22 (4) ◽  
pp. 1572
Author(s):  
Constantin Tănase ◽  
Lucia Pintilie ◽  
Raluca Elena Tănase
Keyword(s):  
Biological Role ◽  
Controlled Synthesis ◽  
Side Chains ◽  
Enzymatic Resolution ◽  
Marine Mollusc ◽  
Enantioselective Reactions ◽  
The Many ◽  
Key Steps

In the total stereo-controlled synthesis of natural prostaglandins (PGs) and their structural analogs, a vast class of compounds and drugs, known as the lactones, are encountered in a few key steps to build the final molecule, as: δ-lactones, γ-lactones, and 1,9-, 1,11-, and 1,15-macrolactones. After the synthesis of 1,9-PGF2α and 1,15-PGF2α lactones, many 1,15-lactones of E2, E3, F2, F3, A2, and A3 were found in the marine mollusc Tethys fimbria and the quest for understanding their biological role stimulated the research on their synthesis. Then 1,9-, 1,11-, and 1,15-PG lactones of the drugs were synthesized as an alternative to the corresponding esters, and the first part of the paper describes the methods used for their synthesis. The efficient Corey procedure for the synthesis of prostaglandins uses the key δ-lactone and γ-lactone intermediates with three or four stereocenters on the cyclopentane fragment to link the PG side chains. The paper describes the most used procedures for the synthesis of the milestone δ-Corey-lactones and γ-Corey-lactones, their improvements, and some new promising methods, such as interesting, new stereo-controlled and catalyzed enantioselective reactions, and methods based on the chemical/enzymatic resolution of the compounds in different steps of the sequences. The many uses of δ-lactones not only for the synthesis of γ-lactones, but also for obtaining 9β-halogen-PGs and halogen-substituted cyclopentane intermediates, as synthons for new 9β-PG analogs and future applications, are also discussed.

Synthesis of New γ-Lactams with gem-Difluorinated Side Chains

Synlett ◽  
2019 ◽  
Vol 30 (20) ◽  
pp. 2258-2262 ◽  
Author(s):  
Ali Soulieman ◽  
Nicolas Gouault ◽  
Thierry Roisnel ◽  
Frédéric Justaud ◽  
Joël Boustie ◽  
...  
Keyword(s):  
Side Chains ◽  
Efficient Approach ◽  
Key Steps ◽  
Nitro Reduction

A short and efficient approach has been designed for the synthesis of new γ-lactams that feature gem-difluorinated side-chains in position 4. The key steps involve 1,4-addition of nitroalkane anions on electrophilic gem-difluoroalkenes, followed by a cascade nitro reduction–heterocyclization. This flexible strategy also allows easy introduction of substituents in positions 3 or 5.

Copolymerization of l-lactide/trimethylene carbonate by organocatalysis: controlled synthesis of comb-like graft copolymers with side chains with different topologies

RSC Advances ◽  
2016 ◽  
Vol 6 (46) ◽  
pp. 40371-40382 ◽  
Author(s):  
Xuefei Leng ◽  
Zhiyong Wei ◽  
Yingying Ren ◽  
Yufei Bian ◽  
Qinyi Wang ◽  
...  
Keyword(s):  
Graft Copolymers ◽  
Controlled Synthesis ◽  
Side Chains ◽  
Trimethylene Carbonate

Synthesis of comb-like graft copolymers of lcP(LLA-co-TMC) from an organocatalyst/PB–OH system: including lcP(TMC-b-LLA), lcP(LLA-grad-TMC) and lcP(LLA-ran-TMC).

scholarly journals Modern methods for investigating the stability of a pitching floating platform wind turbine

2017 ◽  
Vol 2 (2) ◽  
pp. 671-683 ◽  
Author(s):  
Matthew Lennie ◽  
David Marten ◽  
George Pechlivanoglou ◽  
Christian Navid Nayeri ◽  
Christian Oliver Paschereit
Keyword(s):  
Wind Turbine ◽  
Turbine Rotor ◽  
Test Case ◽  
Floating Platform ◽  
Platform Motion ◽  
The Stability ◽  
The Many ◽  
New Formulation ◽  
Key Steps ◽  
Lifting Line

Abstract. The QBlade implementation of the lifting-line free vortex wake (LLFVW) method was tested in conditions analogous to floating platform motion. Comparisons against two independent test cases using a variety of simulation methods show good agreement in thrust forces, rotor power, blade forces and rotor plane induction. Along with the many verifications already undertaken in the literature, it seems that the code performs solidly even in these challenging cases. Further to this, the key steps are presented from a new formulation of the instantaneous aerodynamic thrust damping of a wind turbine rotor. A test case with harmonic platform motion and collective blade pitch is used to demonstrate how combining such tools can lead to a better understanding of aeroelastic stability. A second case demonstrates a non-harmonic blade pitch manoeuvre showing the versatility of the instantaneous damping method.

scholarly journals Identifying the elusive link between amino acid sequence and charge selectivity in pentameric ligand-gated ion channels

2016 ◽  
Vol 113 (45) ◽  
pp. E7106-E7115 ◽  
Author(s):  
Gisela D. Cymes ◽  
Claudio Grosman
Keyword(s):  
Ion Channels ◽  
Careful Analysis ◽  
Side Chains ◽  
Electrophysiological Recordings ◽  
Charge Selectivity ◽  
The Many ◽  
Backbone Atoms ◽  
Charge Sign ◽  
Gated Ion Channels ◽  
Ligand Gated Ion Channels

Among neurotransmitter-gated ion channels, the superfamily of pentameric ligand-gated ion channels (pLGICs) is unique in that its members display opposite permeant-ion charge selectivities despite sharing the same structural fold. Although much effort has been devoted to the identification of the mechanism underlying the cation-versus-anion selectivity of these channels, a careful analysis of past work reveals that discrepancies exist, that different explanations for the same phenomenon have often been put forth, and that no consensus view has yet been reached. To elucidate the molecular basis of charge selectivity for the superfamily as a whole, we performed extensive mutagenesis and electrophysiological recordings on six different cation-selective and anion-selective homologs from vertebrate, invertebrate, and bacterial origin. We present compelling evidence for the critical involvement of ionized side chains—whether pore-facing or buried—rather than backbone atoms and propose a mechanism whereby not only their charge sign but also their conformation determines charge selectivity. Insertions, deletions, and residue-to-residue mutations involving nonionizable residues in the intracellular end of the pore seem to affect charge selectivity by changing the rotamer preferences of the ionized side chains in the first turn of the M2 α-helices. We also found that, upon neutralization of the charged residues in the first turn of M2, the control of charge selectivity is handed over to the many other ionized side chains that decorate the pore. This explains the long-standing puzzle as to why the neutralization of the intracellular-mouth glutamates affects charge selectivity to markedly different extents in different cation-selective pLGICs.

scholarly journals Carbon-free conferencing in the age of COVID-19

2020 ◽  
Vol 49 (4) ◽  
pp. 321-329
Author(s):  
Linda JL Veldhuizen ◽  
Maja Slingerland ◽  
Lauren Barredo ◽  
Ken E Giller
Keyword(s):  
Scientific Knowledge ◽  
Success Factors ◽  
Joint Learning ◽  
Working From Home ◽  
Online Tools ◽  
The Many ◽  
Good Set ◽  
Key Steps ◽  
The Impact

The COVID-19 pandemic has been a crash course for many in working from home using various online tools, many of which can be used to organize e-conferences. An e-conference is a fully online event with multiple sessions and virtual discussion in one platform. In this paper, we aim to provide insights in and present key steps to organize a successful e-conference, increase our understanding of the impact of e-conferences, and identify key strengths, weaknesses, and success factors. Based on a participant survey and our own experience, we found that e-conferences are relatively easy to organize with readily-available and free tools, that they are more accessible and thus inclusive than physical meetings, and that they are virtually carbon-free which can contribute to large emission savings. Three important success factors are attracting a good set of speakers, building an interested audience, and reaching your objectives and desired impact. A successful e-conference can enable joint learning among speakers and participants, and allows novel ways of disseminating scientific knowledge while also enabling networking for the many participants who might not be able to attend an in-person event.

Stereochemically controlled synthesis of steroid side chains: synthesis of desmosterol

1980 ◽  
Vol 45 (6) ◽  
pp. 1172-1174 ◽  
Author(s):  
Masato Koreeda ◽  
Yoshio Tanaka ◽  
Anchel Schwartz
Keyword(s):  
Controlled Synthesis ◽  
Side Chains

Poly[glycidyl oligo(oxyethylene)carbamate]s (PGn-EOmR’ and R-PGn-EOmR’): Controlled Synthesis and Effects of Molecular Parameters (n and m), Side Group (R’), and End-Group (R) on Thermoresponsive Property

2021 ◽  
Author(s):  
Tingyu He ◽  
Yanqiu Wang ◽  
Liang Xu ◽  
Xiangming Fu ◽  
Atsushi Narumi ◽  
...  
Keyword(s):  
Ring Opening ◽  
Glycidyl Ether ◽  
Controlled Synthesis ◽  
Side Chains ◽  
Side Group ◽  
Molecular Parameters ◽  
End Group

The controlled syntheses of glycerol-based polymers that consist of poly(glycidol) (PG)-backbones and thermoresponsive oligo(oxyethylene)-side chains are described. The organocatalytic ring-opening polymerizations of benzyl glycidyl ether (BnGE) were performed to produce...

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