scholarly journals Thiol-Ene Click-Inspired Late-Stage Modification of Long-Chain Polyurethane Dendrimers

Reactions ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 12-29
Author(s):  
Dhruba P. Poudel ◽  
Richard T. Taylor
Keyword(s):  
Late Stage ◽  
Click Reaction ◽  
High Reactivity ◽  
One Pot ◽  
The Core ◽  
Ft Ir ◽  
Curtius Reaction ◽  
Primary Focus ◽  
Simple Molecules

The construction of well-defined polyurethane dendrimers is challenging due to the high reactivity of externally added or in situ formed isocyanates leading to the formation of side products. With a primary focus of dendrimer research being the interaction of the periphery and the core, we report the synthesis of a common polyurethane dendron, which allows for the late-stage variation of both the periphery and the core. The periphery can be varied simply by installing a clickable unit in the dendron and then attaching to the core and vice-versa. Thus, a common dendron allows for varying periphery and core in the final two steps. To accomplish this, a protecting group-free, one-pot multicomponent Curtius reaction was utilized to afford a robust and versatile AB2 type polyurethane dendron employing commercially available simple molecules: 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4-penten-1-ol. Subsequent late-stage modifications of either dendrons or dendrimers via a thiol-ene click reaction gave surface-functionalized alternating aromatic-aliphatic polyurethane homodendrimers to generation-three (G3). The dendrons and the dendrimers were characterized by NMR, mass spectrometry, and FT-IR analysis. A bifunctional AB2 type dendritic monomer demonstrated this approach’s versatility that can either undergo a thiol-ene click or attachment to the core. This approach enables the incorporation of functionalities at the periphery and the core that may not withstand the dendrimer growth for the synthesis of polyurethane dendrimers and other dendritic macromolecules.

scholarly journals Thiol-Ene Click Inspired Late-Stage Modification of Long-Chain Polyurethane Dendrimers

2021 ◽  
Author(s):  
Dhruba Poudel ◽  
Richard Taylor
Keyword(s):  
Late Stage ◽  
Click Reaction ◽  
High Reactivity ◽  
One Pot ◽  
The Core ◽  
Ft Ir ◽  
Curtius Reaction ◽  
Primary Focus ◽  
Simple Molecules

Compared to the synthesis of polyurethane polymers, construction of well-defined polyurethane dendrimers is challenging due to the high reactivity of externally added or in-situ formed isocyanates leading to the formation of side products. For this reason, the synthesis of dendritic polyurethanes is limited to very few reports. With primary focus of dendrimer research on the interaction of the periphery and the core, we report the synthesis of a common polyurethane dendron, which allows for late-stage variation of both the periphery and the core. The periphery can be varied simply by installing a clickable unit in the dendron and then attaching to the core and vice-versa. Thus, a common dendron allows for varying periphery and core in just two steps. To accomplish this, protecting group free one-pot multicomponent Curtius reaction was utilized to afford a robust and versatile AB2 type polyurethane dendron employing commercially available simple molecules 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4- penten-1-ol. Subsequent late-stage modification of either dendrons or dendrimers via thiol-ene click reaction gave surface?functionalized alternating aromatic-aliphatic polyurethane homodendrimers to generation-three (G3). The dendrons and the dendrimers were characterized by NMR, mass spectrometry, and FT-IR analysis. A bifunctional AB2 type dendritic monomer demonstrated this approach's versatility that can either undergo a thiol-one click or attachment to the core. This approach enables the incorporation of functionalities at the periphery and the core that may not withstand the dendrimer growth for the synthesis of polyurethane dendrimers and other dendritic macromolecules

scholarly journals Thiol-Ene Click Inspired Late-Stage Modification of Long-Chain Polyurethane Dendrimers

2021 ◽  
Author(s):  
Dhruba Poudel ◽  
Richard Taylor
Keyword(s):  
Late Stage ◽  
Click Reaction ◽  
High Reactivity ◽  
One Pot ◽  
The Core ◽  
Ft Ir ◽  
Curtius Reaction ◽  
Primary Focus ◽  
Simple Molecules

Compared to the synthesis of polyurethane polymers, construction of well-defined polyurethane dendrimers is challenging due to the high reactivity of externally added or in-situ formed isocyanates leading to the formation of side products. For this reason, the synthesis of dendritic polyurethanes is limited to very few reports. With primary focus of dendrimer research on the interaction of the periphery and the core, we report the synthesis of a common polyurethane dendron, which allows for late-stage variation of both the periphery and the core. The periphery can be varied simply by installing a clickable unit in the dendron and then attaching to the core and vice-versa. Thus, a common dendron allows for varying periphery and core in just two steps. To accomplish this, protecting group free one-pot multicomponent Curtius reaction was utilized to afford a robust and versatile AB2 type polyurethane dendron employing commercially available simple molecules 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4- penten-1-ol. Subsequent late-stage modification of either dendrons or dendrimers via thiol-ene click reaction gave surface?functionalized alternating aromatic-aliphatic polyurethane homodendrimers to generation-three (G3). The dendrons and the dendrimers were characterized by NMR, mass spectrometry, and FT-IR analysis. A bifunctional AB2 type dendritic monomer demonstrated this approach's versatility that can either undergo a thiol-one click or attachment to the core. This approach enables the incorporation of functionalities at the periphery and the core that may not withstand the dendrimer growth for the synthesis of polyurethane dendrimers and other dendritic macromolecules

scholarly journals A Model for Late-Stage Modification of Polyurethane Dendrimers Using Thiol-Ene Click Chemistry

2021 ◽  
Author(s):  
Dhruba Poudel ◽  
Richard Taylor
Keyword(s):  
Click Chemistry ◽  
Late Stage ◽  
Click Reaction ◽  
Synthetic Approach ◽  
Protecting Group ◽  
One Pot ◽  
The Core ◽  
Curtius Reaction

Protecting group free, one-pot multicomponent Curtius reaction was utilized to afford diurethane G-1 dendron. In our synthetic approach, G-1 dendron can undergo late-stage modification using thiol-ene click reaction, which was then attached to the core to furnish a dendrimer. In another approach, the G-1 dendron was attached to the core and so formed dendrimer was surface functionalized using thiol-ene click chemistry. Either way, we can synthesize the dendrimer.

scholarly journals A Model for Late-Stage Modification of Polyurethane Dendrimers Using Thiol-Ene Click Chemistry

2021 ◽  
Author(s):  
Dhruba Poudel ◽  
Richard Taylor
Keyword(s):  
Click Chemistry ◽  
Late Stage ◽  
Click Reaction ◽  
Synthetic Approach ◽  
Protecting Group ◽  
One Pot ◽  
The Core ◽  
Curtius Reaction

Protecting group free, one-pot multicomponent Curtius reaction was utilized to afford diurethane G-1 dendron. In our synthetic approach, G-1 dendron can undergo late-stage modification using thiol-ene click reaction, which was then attached to the core to furnish a dendrimer. In another approach, the G-1 dendron was attached to the core and so formed dendrimer was surface functionalized using thiol-ene click chemistry. Either way, we can synthesize the dendrimer.

Copper Aluminate Spinel in Click Chemistry: An Efficient Heterogeneous Nanocatalyst for the Highly Regioselective Synthesis of Triazoles in Water

Synlett ◽  
2019 ◽  
Vol 30 (19) ◽  
pp. 2136-2142 ◽  
Author(s):  
Dariush Khalili ◽  
Leila Kavoosi ◽  
Ali Khalafi-Nezhad
Keyword(s):  
Aqueous Medium ◽  
Click Reaction ◽  
One Pot ◽  
Organic Azides ◽  
Heterogeneous Catalytic ◽  
Heterogeneous Catalytic System ◽  
Simple Filtration ◽  
Copper Aluminate ◽  
The One

An expeditious protocol for the one-pot synthesis of 1,4-disubstituted (β-hydroxy)-1,2,3-triazoles in an aqueous medium has been developed using copper aluminate nanoparticles. This heterogeneous catalytic system was found to drive a multicomponent click reaction between organic azides (generated in situ from epoxides or halides) and terminal aliphatic or aromatic alkynes in up to 96% yield without the need for a reducing agent. Structurally diverse 1,2,3-triazoles were synthesized in good to excellent yields, and the catalyst could be easily separated by simple filtration, recycled, and reused in six subsequent cycles.

Insight into growth of Au–Pt bimetallic nanoparticles: anin situXAS study

2017 ◽  
Vol 24 (4) ◽  
pp. 825-835 ◽  
Author(s):  
Chandrani Nayak ◽  
D. Bhattacharyya ◽  
K. Bhattacharyya ◽  
A. K. Tripathi ◽  
R. D. Bapat ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Energy Dispersive ◽  
Core Shell ◽  
One Pot ◽  
X Ray ◽  
The Core ◽  
One Pot Synthesis ◽  
X Ray Absorption ◽  
Insight Into

Au–Pt bimetallic nanoparticles have been synthesized through a one-pot synthesis route from their respective chloride precursors using block copolymer as a stabilizer. Growth of the nanoparticles has been studied by simultaneousin situmeasurement of X-ray absorption spectroscopy (XAS) and UV–Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at Indus-2 SRS at RRCAT, Indore, India.In situXAS spectra, comprising both X-ray near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) parts, have been measured simultaneously at the Au and PtL3-edges. While the XANES spectra of the precursors provide real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed in the intermediate stages of growth. This insight into the formation process throws light on how the difference in the reduction potential of the two precursors could be used to obtain the core–shell-type configuration of a bimetallic alloy in a one-pot synthesis method. The core–shell-type structure of the nanoparticles has also been confirmed byex situenergy-dispersive spectroscopy line-scan and X-ray photoelectron spectroscopy measurements within situion etching on fully formed nanoparticles.

scholarly journals Synthesis of New 5-Aryl-benzo[f][1,7]naphthyridines via a Cascade Process (Ugi-3CR/Intramolecular Aza-Diels-Alder Cycloaddition)/Aromatization

Molecules ◽  
2018 ◽  
Vol 23 (8) ◽  
pp. 2029
Author(s):  
Óscar Vázquez-Vera ◽  
Daniel Segura-Olvera ◽  
Mónica Rincón-Guevara ◽  
Atilano Gutiérrez-Carrillo ◽  
Miguel García-Sánchez ◽  
...  
Keyword(s):  
Oxidation Process ◽  
Diels Alder ◽  
Cascade Process ◽  
Chain Ring ◽  
One Pot ◽  
The Core ◽  
Sar Studies ◽  
Starting Point ◽  
Three Component Reaction

A series of eight new 5-aryl-benzo[f][1,7]naphthyridines were synthesized in 17 to 64% overall yields via an improved MW-assisted cascade-like one pot process (Ugi–three component reaction/intramolecular aza-Diels-Alder cycloaddition) coupled to an aromatization process from tri-functional dienophile-containing ester-anilines, substituted benzaldehydes and the chain-ring tautomerizable 2-isocyano-1-morpholino-3-phenylpropan-1-one as starting reagents, under mild conditions. The doubly activated dienophile and the aza-diene functionalities of the eight new Ugi-adducts were exploited to perform an in situ aza-Diels-Alder cycloaddition/aromatization (dehydration/oxidation) process, toward the complex polysubstituted 5-aryl-polyheterocycles, which could be taken as starting point for further SAR studies because the benzo[f][1,7]naphthyridine is the core of various bioactive products. It is relevant to emphasize that the synthesis or isolation of benzo[f][1,7]naphthyridines containing a substituted aromatic ring in the C-5 position, has not been published before.

FT-IR microspectroscopic analysis of diseased white matter brain tissues

1995 ◽  
Vol 53 ◽  
pp. 968-969
Author(s):  
Steven M. Le Vine ◽  
David L. Wetzel
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Twitcher Mouse ◽  
Grid Pattern ◽  
Marked Contrast ◽  
Spatially Resolved ◽  
Ft Ir ◽  
Ir Microspectroscopy ◽  
Chemical Evidence

In situ FT-IR microspectroscopy has allowed spatially resolved interrogation of different parts of brain tissue. In previous work the spectrrscopic features of normal barin tissue were characterized. The white matter, gray matter and basal ganglia were mapped from appropriate peak area measurements from spectra obtained in a grid pattern. Bands prevalent in white matter were mostly associated with the lipid. These included 2927 and 1469 cm-1 due to CH2 as well as carbonyl at 1740 cm-1. Also 1235 and 1085 cm-1 due to phospholipid and galactocerebroside, respectively (Figs 1and2). Localized chemical changes in the white matter as a result of white matter diseases have been studied. This involved the documentation of localized chemical evidence of demyelination in shiverer mice in which the spectra of white matter lacked the marked contrast between it and gray matter exhibited in the white matter of normal mice (Fig. 3).The twitcher mouse, a model of Krabbe’s desease, was also studied. The purpose in this case was to look for a localized build-up of psychosine in the white matter caused by deficiencies in the enzyme responsible for its breakdown under normal conditions.

A Revised Modular Approach to D8-THC and Derivatives Through Late-Stage Suzuki-Miyaura Cross-Coupling Reactions

2019 ◽  
Author(s):  
Victor Bloemendal ◽  
Floris P. J. T. Rutjes ◽  
Thomas J. Boltje ◽  
Daan Sondag ◽  
Hidde Elferink ◽  
...  
Keyword(s):  
Biological Activity ◽  
Late Stage ◽  
Medicinal Chemistry ◽  
Cross Coupling ◽  
Modular Approach ◽  
Coupling Reactions ◽  
One Pot ◽  
Biologically Relevant ◽  
Cross Coupling Reactions ◽  
Chemistry Research

<p>In this manuscript we describe a modular pathway to synthesize biologically relevant (–)-<i>trans</i>-Δ<sup>8</sup>-THC derivatives, which can be used to modulate the pharmacologically important CB<sub>1</sub> and CB<sub>2</sub> receptors. This pathway involves a one-pot Friedel-Crafts alkylation/cyclization protocol, followed by Suzuki-Miyaura cross-coupling reactions and gives rise to a series of new Δ<sup>8</sup>-THC derivatives. In addition, we demonstrate using extensive NMR evidence that similar halide-substituted Friedel-Crafts alkylation/cyclization products in previous articles were wrongly assigned as the para-isomers, which also has consequence for the assignment of the subsequent cross-coupled products and interpretation of their biological activity. </p> <p>Considering the importance of the availability of THC derivatives in medicinal chemistry research and the fact that previously synthesized compounds were wrongly assigned, we feel this research is describing a straightforward pathway into new cannabinoids.</p>

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