scholarly journals Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes

2021 ◽  
Vol 17 ◽  
pp. 2773-2780
Author(s):  
Nicolai Wippert ◽  
Martin Nieger ◽  
Claudine Herlan ◽  
Nicole Jung ◽  
Stefan Bräse
Keyword(s):  
Building Blocks ◽  
Side Chains ◽  
Protective Group ◽  
Cleavage Reaction

We describe the synthesis of so far synthetically not accessible 3,6-substituted-4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines as nitrogen-rich heterocycles. The target compounds were obtained in five steps, including an amidation and a cyclative cleavage reaction as key reaction steps. The introduction of two side chains allowed a variation of the pyrazolo[3,4-d][1,2,3]triazine core with commercially available building blocks, enabling the extension of the protocol to gain other derivatives straightforwardly. Attempts to synthesize 3,7-substituted-4,7-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines, the regioisomers of the successfully gained 3,6-substituted 4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines, were not successful under similar conditions due to the higher stability of the triazene functionality in the regioisomeric precursors and thus, the failure of the removal of the protective group.

scholarly journals Synthesis of new pyrazolo[1,2,3]triazines by cyclative cleavage of pyrazolyltriazenes

2021 ◽  
Author(s):  
Nicolai Wippert ◽  
Martin Nieger ◽  
Claudine Herlan ◽  
Nicole Jung ◽  
Stefan Bräse
Keyword(s):  
Building Blocks ◽  
Side Chains ◽  
Protective Group ◽  
Cleavage Reaction

We describe the synthesis of so far synthetically not accessible 3,6-substituted-4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines as nitrogen-rich heterocycles. The target compounds were obtained in five steps, including an amidation and a cyclative cleavage reaction as key reaction steps. The introduction of two side-chains allowed a variation of the pyrazolo[3,4-d][1,2,3]triazine-core with commercially available building blocks, enabling the extension of the protocol to gain other derivatives straightforwardly. Attempts to synthesize 3,7-substituted-4,7-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazines, the regio-isomers of the successfully gained 3,6-substituted-4,6-dihydro-3H-pyrazolo[3,4-d][1,2,3]-3H-triazines, were not successful under similar conditions due to the higher stability of the triazene functionality in the regio-isomeric precursors and thus the failure of the removal of the protective group.

scholarly journals Acrylamides with hydrolytically labile carbonate ester side chains as versatile building blocks for well-defined block copolymer micelles via RAFT polymerization

2017 ◽  
Vol 8 (42) ◽  
pp. 6544-6557 ◽  
Author(s):  
Sabah Kasmi ◽  
Benoit Louage ◽  
Lutz Nuhn ◽  
Glenn Verstraete ◽  
Simon Van Herck ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Raft Polymerization ◽  
Building Blocks ◽  
Side Chains ◽  
Hydrophobic Modification ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

Hydrophobic modification of N-(2-hydroxyethyl)acrylamide yields a class of building blocks that is attractive for biomaterial synthesis.

3-Alkylated (R)-2,3-Dihydroxyalkyl p-Toluenesulfonates - homochiral building blocks for modified steroid side chains

1990 ◽  
Vol 332 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Eberhard Schrötter ◽  
Tran Thanh Luong ◽  
Hans Schick
Keyword(s):  
Building Blocks ◽  
Side Chains

ChemInform Abstract: 3-Alkylated (R)-2,3-Dihydroxyalkyl p-Toluenesulfonates - Homochiral Building Blocks for Modified Steroid Side Chains.

ChemInform ◽  
1990 ◽  
Vol 21 (43) ◽  
Author(s):  
E. SCHROETTER ◽  
TRAN THANH LUONG TRAN THANH LUONG ◽  
H. SCHICK
Keyword(s):  
Building Blocks ◽  
Side Chains

scholarly journals Adsorption Properties of Soft Hydrophobically Functionalized PSS/MA Polyelectrolytes

2021 ◽  
Vol 5 (1) ◽  
pp. 3
Author(s):  
Ewelina Jarek ◽  
Zofia Krasińska-Krawet ◽  
Tomasz Kruk ◽  
Łukasz Lamch ◽  
Sylwia Ronka ◽  
...  
Keyword(s):  
Solid Surface ◽  
Alkyl Chain ◽  
Water Structure ◽  
Building Blocks ◽  
Adsorption Properties ◽  
Attenuated Total Reflection ◽  
Side Chains ◽  
Adsorption Method ◽  
Present Contribution ◽  
Grafting Ratio

We investigated the adsorption properties of the newly synthesized, hydrophobically functionalized polyelectrolyte (HF-PE), poly(4-styrenesulfonic-co-maleic acid) copolymer (PSS/MA). The hydrophobic alkyl side chains (C12 or C16) were incorporated into the polyelectrolyte backbone via the labile amid linker to obtain the soft HF-PE product with the assumed amount of 15% and 40% degree of grafting for every length of the alkyl chain, i.e., PSS/MA-g-C12NH2 (15% or 40%) as well as PSS/MA-g-C16NH2 (15% or 40%). In the present contribution, we determined both the effect of grafting density and the length of alkyl chain on adsorption at water/air and water/decane interfaces, as well as on top of the polyelectrolyte multilayer (PEM) deposited on a solid surface. The dependence of the interfacial tension on copolymer concentration was investigated by the pendant drop method, while the adsorption at solid surface coated by poly(diallyldimethylammonium chloride)/poly(styrene sulphonate) PEM by the quartz crystal microbalance with dissipation (QCM-D), attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) and contact angle analysis. We found that surface activity of the hydrophobized copolymer was practically independent of the grafting ratio for C16 side chains, whereas, for C12, the copolymer with a lower grafting ratio seemed to be more surface active. The results of QCM-D and FTIR-ATR experiments confirmed the adsorption of hydrophobized copolymer at PEM along with the modification of water structure at the interface. Finally, it can be concluded that the hydrophobically modified PSS/MA can be successfully applied either as the efficacious emulsifier for the formation of (nano)emulsions for further active substances encapsulation using the sequential adsorption method or as one of the convenient building blocks for the surface modification materials.

scholarly journals Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

2017 ◽  
Vol 13 ◽  
pp. 2094-2114 ◽  
Author(s):  
Weizhun Yang ◽  
Bo Yang ◽  
Sherif Ramadan ◽  
Xuefei Huang
Keyword(s):  
Building Blocks ◽  
Sialic Acids ◽  
Uronic Acids ◽  
Protective Group ◽  
One Pot ◽  
Donor And Acceptor ◽  
Glycosyl Donor ◽  
Complex Glycans ◽  
Powerful Strategy ◽  
Multiple Step

Most glycosylation reactions are performed by mixing the glycosyl donor and acceptor together followed by the addition of a promoter. While many oligosaccharides have been synthesized successfully using this premixed strategy, extensive protective group manipulation and aglycon adjustment often need to be performed on oligosaccharide intermediates, which lower the overall synthetic efficiency. Preactivation-based glycosylation refers to strategies where the glycosyl donor is activated by a promoter in the absence of an acceptor. The subsequent acceptor addition then leads to the formation of the glycoside product. As donor activation and glycosylation are carried out in two distinct steps, unique chemoselectivities can be obtained. Successful glycosylation can be performed independent of anomeric reactivities of the building blocks. In addition, one-pot protocols have been developed that have enabled multiple-step glycosylations in the same reaction flask without the need for intermediate purification. Complex glycans containing both 1,2-cis and 1,2-trans linkages, branched oligosaccharides, uronic acids, sialic acids, modifications such as sulfate esters and deoxy glycosides have been successfully synthesized. The preactivation-based chemoselective glycosylation is a powerful strategy for oligosaccharide assembly complementing the more traditional premixed method.

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