41158-32-1Relevant articles and documents
A Self-Catalyzed Visible Light Driven Thiol Ligation
Rodrigues, Leona L.,Micallef, Aaron S.,Pfrunder, Michael C.,Truong, Vinh X.,McMurtrie, John C.,Dargaville, Tim R.,Goldmann, Anja S.,Feist, Florian,Barner-Kowollik, Christopher
, p. 7292 - 7297 (2021)
We introduce a highly efficient ligation system based on a visible light-induced rearrangement affording a thiophenol which rapidly undergoes thiol-Michael additions. Unlike conventional light-triggered thiol-ene/yne systems, which rely on the use of photocaged bases/nucleophiles, (organo)-photo catalysts, or radical photoinitiators, our system provides a light-induced reaction in the absence of any additives. The ligation is self-catalyzed via the pyridine mediated deprotonation of the photochemically generated thiophenol. Subsequently, the thiol-Michael reaction between the thiophenol anion and electron deficient alkynes/alkenes proceeds additive-free. Hereby, the underlying photoinduced rearrangement of o-thiopyrinidylbenzaldehyde (oTPyB) generating the free thiol is described for the first time. We studied the influence of various reactions conditions as well as solvents and substrates. We exemplify our findings in a polymer end group modification and obtained macromolecules with excellent end group fidelity.
Synthesis of New γ-Lactams with gem-Difluorinated Side Chains
Boustie, Jo?l,Gouault, Nicolas,Greé, René,Hachem, Ali,Justaud, Frédéric,Roisnel, Thierry,Soulieman, Ali
, p. 2258 - 2262 (2019/12/11)
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.
Relative Rates of Metal-Free Azide-Alkyne Cycloadditions: Tunability over 3 Orders of Magnitude
Skelly, Patrick W.,Sae-Jew, Jirapon,Kitos Vasconcelos, Ana Paula,Tasnim, Jerin,Li, Longbo,Raskatov, Jevgenij A.,Braslau, Rebecca
, p. 13615 - 13623 (2019/11/14)
The thermal (3 + 2) dipolar azide-alkyne cycloaddition, proceeding without copper or strained alkynes, is an underutilized ligation with potential applications in materials, bioorganic, and synthetic chemistry. Herein, we investigate the effects of alkyne substitution on the rate of this reaction, both experimentally and computationally. Electron-withdrawing groups accelerate the reaction, providing a range of relative rates from 1.0 to 2100 between the slowest and fastest alkynes studied. Unexpectedly, aryl groups conjugated to the alkyne significantly retard the reaction rate. In contrast, a sulfonyl, ester-substituted alkyne is reactive enough that it couples with an azide at room temperature in a few hours. This reactivity scale should provide a guide to those who wish to use this ligation under mild conditions.
