Inverse Electron Demand Diels-Alder Reactions of Heterocyclic Azadienes: [4 + 2] Cycloaddition Reaction of Amidines with 1,3,5-Triazines

1994 ◽  
Vol 59 (17) ◽  
pp. 4950-4955 ◽  
Author(s):  
Dale L. Boger ◽  
Monica J. Kochanny
Keyword(s):  
Cycloaddition Reaction ◽  
Diels Alder ◽  
Inverse Electron Demand ◽  
Electron Demand

Potassium Arylethynyltrifluoroborate as an Unstrained Dienophile for Ultrafast and On Demand Activation of Bioorthogonal IEDDA Reactions

2019 ◽  
Author(s):  
Zijian Guo ◽  
Bruno Oliveira ◽  
Claudio D. Navo ◽  
Pedro M. S. D. Cal ◽  
Francisco Corzana ◽  
...  
Keyword(s):  
Protein Modification ◽  
Cross Reactivity ◽  
Diels Alder ◽  
Inverse Electron Demand ◽  
On Demand ◽  
Strained Alkenes ◽  
Electron Demand

<p>Strained alkenes and alkynes are the predominant dienophiles used in inverse electron-demand Diels-Alder (IEDDA) reactions, however, their instability, cross-reactivity and accessibility are problematic. Unstrained dienophiles, although physiologically stable and synthetically accessible, react with tetrazines significantly slower relative to strained variants. Here we report the development of potassium arylethynyltrifluoroborates as unstrained dienophiles for ultrafast, chemically triggered IEDDA reactions. By varying the substituents on the tetrazine (e.g. pyridyl- to benzyl-substituents), cycloaddition rates can vary from nearly spontaneous (<i>t</i><sub>1/2</sub>≈ 9 s) to no reaction with the unstrained alkyne-BF3 dienophile. The reported system was applied to protein modification and enabled mutually orthogonal labelling of two distinct proteins.</p>

Potassium Arylethynyltrifluoroborate as an Unstrained Dienophile for Ultrafast and On Demand Activation of Bioorthogonal IEDDA Reactions

2019 ◽  
Author(s):  
Zijian Guo ◽  
Bruno Oliveira ◽  
Claudio D. Navo ◽  
Pedro M. S. D. Cal ◽  
Francisco Corzana ◽  
...  
Keyword(s):  
Protein Modification ◽  
Cross Reactivity ◽  
Diels Alder ◽  
Inverse Electron Demand ◽  
On Demand ◽  
Strained Alkenes ◽  
Electron Demand

<p>Strained alkenes and alkynes are the predominant dienophiles used in inverse electron-demand Diels-Alder (IEDDA) reactions, however, their instability, cross-reactivity and accessibility are problematic. Unstrained dienophiles, although physiologically stable and synthetically accessible, react with tetrazines significantly slower relative to strained variants. Here we report the development of potassium arylethynyltrifluoroborates as unstrained dienophiles for ultrafast, chemically triggered IEDDA reactions. By varying the substituents on the tetrazine (e.g. pyridyl- to benzyl-substituents), cycloaddition rates can vary from nearly spontaneous (<i>t</i><sub>1/2</sub>≈ 9 s) to no reaction with the unstrained alkyne-BF3 dienophile. The reported system was applied to protein modification and enabled mutually orthogonal labelling of two distinct proteins.</p>

Synthese neuer Pyridin-C-nukleoside der 2 ,3 -Didesoxyribose durch „inverse“ [4+2]-Cycloaddition Synthesis of Novel Pyridine-C-nucleosides of 2,3-Dideoxyribose by „Inverse“ [4+2]-Cycloaddition

1997 ◽  
Vol 52 (7) ◽  
pp. 851-858 ◽  
Author(s):  
Gunther Seitz ◽  
Johanna Siegl
Keyword(s):  
Cycloaddition Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Novel ◽  
Protecting Group ◽  
Enol Ethers ◽  
Inverse Electron Demand ◽  
Diels Alder Reaction ◽  
Cyclic Ketene Acetals

The anomeric imido esters 5 and 6, appropriate precursors for C-nucleoside synthesis, were prepared and utilized as heterodienophiles in a Diels-Alder reaction with inverse electron demand to yield the novel, protected 1.2.4-triazine C-nucleosides 8 and 9. They could be deprotected by treatment with 70% trifluoroacetic acid to furnish the free C-nucleosides 10 and 11. The triazine „aglycon“ of 8 contains an electron deficient diazadiene system, highly activated to react with various electron rich dienophiles such as enamines, enol ethers and several cyclic ketene acetals in an „inverse“ [4+2]-cycloaddition reaction. The Diels-Alder adducts spontaneously eliminate N2 and after follow-up reactions the O-TBDPS protected pyridine-C-nucleosides 13, 15, 17,19, 21 and 23 are formed. Removal of the protecting group by treatment with CF3CO2H /H2O leads to the corresponding 2’,3’-dideoxy-β-D-ribofuranosyl- pyridines.

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