82504-06-1Relevant academic research and scientific papers
Pd-Catalyzed ipso, meta-Dimethylation of ortho-Substituted Iodoarenes via a Base-Controlled C-H Activation Cascade with Dimethyl Carbonate as the Methyl Source
Wu, Zhuo,Wei, Feng,Wan, Bin,Zhang, Yanghui
supporting information, p. 4524 - 4530 (2021/05/04)
A methyl group can have a profound impact on the pharmacological properties of organic molecules. Hence, developing methylation methods and methylating reagents is essential in medicinal chemistry. We report a palladium-catalyzed dimethylation reaction of ortho-substituted iodoarenes using dimethyl carbonate as a methyl source. In the presence of K2CO3 as a base, iodoarenes are dimethylated at the ipso- and meta-positions of the iodo group, which represents a novel strategy for meta-C-H methylation. With KOAc as the base, subsequent oxidative C(sp3)-H/C(sp3)-H coupling occurs; in this case, the overall transformation achieves triple C-H activation to form three new C-C bonds. These reactions allow expedient access to 2,6-dimethylated phenols, 2,3-dihydrobenzofurans, and indanes, which are ubiquitous structural motifs and essential synthetic intermediates of biologically and pharmacologically active compounds.
NUCLIDE LABELLED H-TETRAZINES AND USE THEREOF FOR PET AND SPECT PRETARGETED IMAGING AND RADIONUCLIDE THERAPY
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Page/Page column 48, (2021/11/20)
The present invention relates to novel tetrazine compounds for use in pretargeted in vivo imaging and in therapy and to the precursors of the tetrazine compounds. The compounds are suitable for use in click chemistry, i.e. reactions that join a targeting
Gold(I)-catalyzed iodination of arenes
Leboeuf, David,Ciesielski, Jennifer,Frontier, Alison J.
supporting information, p. 399 - 402 (2014/03/21)
A wide variety of electron-rich arenes were efficiently converted into the corresponding iodinated compounds via a gold(I)-catalyzed reaction under mild conditions. Georg Thieme Verlag Stuttgart. New York.
The element effect and nucleophilicity in nucleophilic aromatic photosubstitution (SNAR*). Local atom effects as mechanistic probes of very fast reactions
Wubbels, Gene G.,Brown, Toby R.,Babcock, Travis A.,Johnson, Kandra M.
, p. 1925 - 1934 (2008/09/19)
(Chemical Equation Presented) Photoreactions of 4-nitroanisole and the 2-halo-4-nitroanisoles (halogen = F, Cl, Br, and I) with the nucleophiles hydroxide ion and pyridine have been investigated quantitatively to extend the findings recently communicated for cyanide ion. The halonitroanisoles on excitation form triplet π,π* states, which undergo substitution of the halogen by nucleophiles. Chemical yields of photoproducts, Stern-Volmer kinetic plots, triplet lifetimes, and triplet yields are reported for the five compounds with the three nucleophiles. Following a standard kinetic treatment, 73 rate constants are determined for elementary reactions of the triplets including quenching and various nucleophilic addition processes. The photoadditions are roughly 14 orders of magnitude faster than thermal counterparts. Rate constants for attack at the fluorine-bearing carbon of triplet 2-fluoro-4-nitroanisole are 2.9 × 109, 1.3 × 109, and 6.3 × 108 M-1 s-1 for cyanide ion, hydroxide ion, and pyridine, respectively. The relative rates for attack at the halogen-bearing carbons for F/Cl/Br/I are 27:1.9:1.9:1 (cyanide ion), 29:2.6:2.4:1 (hydroxide ion), and 39:3.9: 3.5:1 (pyridine), respectively. The relative nucleophilicities vary somewhat with the attack site; they are about 5:2:1 for cyanide ion, hydroxide ion, and pyridine for attack at the halogen-bearing carbons. The trend of the element effect opposes that of aliphatic substitution and elimination but is similar in size and parallel to that of thermal nucleophilic aromatic substitution. Relative nucleophilicities in the photoreactions are also similar to those of comparable but vastly slower thermal reactions. The findings imply that the efficiency-determining step of the halogen photosubstitution is simple formation of a σ-complex through electron-paired bonding within the triplet manifold.
The element effect in nucleophilic aromatic photosubstitution (S N2Ar*)
Wubbels, Gene G.,Johnson, Kandra M.,Babcock, Travis A.
, p. 2803 - 2806 (2008/02/05)
Photoreactions of 4-nitroanisole and the 2-halo-4-nitroanisoles (halogen == F, Cl, Br, I) with NaCN have been investigated. 4-Nitroanisole gave a novel, stable nitronate ion adduct (74%) with cyanide. For the five compounds, we report product distributions, Stern-Volmer kinetic plots, triplet lifetimes, and triplet yields, which afford rate constants for attack by the cyanide ion. Cyanide attack on the fluoride is diffusion controlled; the relative rates for attack at F, Cl, Br, and I are 27:2:2:1, respectively.
MACROLIDE CLOSURE VIA FLUORODESILYLATION. A TOTAL SYNTHESIS OF d,l-17-O-METHYLLYTHRIDINE
Seitz, David E.,Milius, Richard A.,Quick, James
, p. 1439 - 1442 (2007/10/02)
A synthesis of the macrolide 17-O-methyllythridine is reported in which cyclization is initiated by fluorodesilylation of a trimethylsilylacetate.
