142651-24-9Relevant articles and documents
Kinetic model studies on the chemical ligation of oligonucleotides via hydrazone formation
Achilles,Kiedrowski
, p. 1229 - 1233 (2005)
We report on the suitability of hydrazone formation for activator-free ligation of oligonucleotides. 5′-Acyl hydrazides were synthesized using a previously described phosphoramidite modifier, whereas 3′-hydrazides resulted from a hydrazinolysis of an ester group serving as a linker to the solid support. Aromatic aldehydes could be directly introduced on the 5′-terminus via the respective phosphoramidates. Aliphatic aldehydes were generated by periodate cleavage of the corresponding 3′- and 5′-modified diol precursors. Ligation of a 3′-hydrazide-modified oligonucleotide with oligonucleotides bearing an aromatic aldehyde in 5′-position showed a fast reaction kinetics (k1 about 10 -1) and irreversible hydrazone formation. The ligation of a 5′-hydrazide-modified oligonucleotide and a 3′-ribobisaldehyde appeared to proceed reversibly at the beginning, but became irreversible with increasing reaction time. Hydrazide-modified oligonucleotides were found to be somewhat unstable in aqueous solutions.
PHOTOCATALYST SYSTEM AND USE THEREOF IN A PHOTOCATALYTIC PROCESS
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Page/Page column 33; 35; 37, (2019/06/13)
Photocatalyst system and use thereof in a photochemical process The invention relates to a photocatalyst system comprising, in the absence of a further photosensitizer other than the compound of formula (III) or a mixture thereof: (i) a nickel(II) salt, (
Sp3 C-H Arylation and Alkylation Enabled by the Synergy of Triplet Excited Ketones and Nickel Catalysts
Shen, Yangyang,Gu, Yiting,Martin, Ruben
supporting information, p. 12200 - 12209 (2018/09/27)
Triplet ketone sensitizers are of central importance within the realm of photochemical transformations. Although the radical-type character of triplet excited states of diaryl ketones suggests the viability for triggering hydrogen-atom transfer (HAT) and single-electron transfer (SET) processes, among others, their use as multifaceted catalysts in C-C bond-formation via sp3 C-H functionalization of alkane feedstocks still remains rather unexplored. Herein, we unlock a modular photochemical platform for forging C(sp3)-C(sp2) and C(sp3)-C(sp3) linkages from abundant alkane sp3 C-H bonds as functional handles using the synergy between nickel catalysts and simple, cheap and modular diaryl ketones. This method is distinguished by its wide scope that is obtained from cheap catalysts and starting precursors, thus complementing existing inner-sphere C-H functionalization protocols or recent photoredox scenarios based on iridium polypyridyl complexes. Additionally, such a platform provides a new strategy for streamlining the synthesis of complex molecules with high levels of predictable site-selectivity and preparative utility. Mechanistic experiments suggest that sp3 C-H abstraction occurs via HAT from the ketone triplet excited state. We believe this study will contribute to a more systematic utilization of triplet excited ketones as catalysts in metallaphotoredox scenarios.
