5669-14-7Relevant articles and documents
Diradicals Photogeneration from Chloroaryl-Substituted Carboxylic Acids
Di Terlizzi, Lorenzo,Protti, Stefano,Ravelli, Davide,Fagnoni, Maurizio
, (2022/04/09)
With the aim of generating new, thermally inaccessible diradicals, potentially able to induce a double-strand DNA cleavage, the photochemistry of a set of chloroaryl-substituted carboxylic acids in polar media was investigated. The photoheterolytic cleavage of the Ar?Cl bond occurred in each case to form the corresponding triplet phenyl cations. Under basic conditions, the photorelease of the chloride anion was accompanied by an intramolecular electron-transfer from the carboxylate group to the aromatic radical cationic site to give a diradical species. This latter intermediate could then undergo CO2 loss in a structure-dependent fashion, according to the stability of the resulting diradical, or abstract a hydrogen atom from the medium. In aqueous environment at physiological pH (pH=7.3), both a phenyl cation and a diradical chemistry was observed. The mechanistic scenario and the role of the various intermediates (aryl cations and diradicals) involved in the process was supported by computational analysis.
SUBSTITUTED, SATURATED AND UNSATURATED N-HETEROCYCLIC CARBOXAMIDES AND RELATED COMPOUNDS FOR THEIR USE IN THE TREATMENT OF MEDICAL DISORDERS
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, (2021/04/01)
The invention provides substituted, saturated and unsaturated N-heterocyclic carboxamides and related compounds, compositions containing such compounds, medical kits, and methods for using such compounds and compositions to treat medical disorders, e.g., cancer, lysosomal storage disorder, neurodegenerative disorder, inflammatory disorder, in a patient.
Mechanism of 8-Aminoquinoline-Directed Ni-Catalyzed C(sp3)-H Functionalization: Paramagnetic Ni(II) Species and the Deleterious Effect of Carbonate as a Base
Liu, Junyang,Johnson, Samuel A.
supporting information, p. 2970 - 2982 (2021/06/28)
Studies into the mechanism of 8-aminoquinoline-directed nickel-catalyzed C(sp3)-H arylation with iodoarenes were carried out, to determine the catalyst resting state and optimize catalytic performance. Paramagnetic complexes undergo the key C-H activation step. The ubiquitous base Na2CO3is found to hinder catalysis; replacement of Na2CO3with NaOtBu gave improved catalytic turnovers under milder conditions. Deprotonation of the 8-aminoquinoline derivativeN-(quinolin-8-yl)pivalamide (1a) at the amide nitrogen using NaH, followed by reaction with NiCl2(PPh3)2allowed for the isolation of complex Ni([AQpiv]-κN,N)2(3) with chelating N-donors (where [AQpiv] = C9NH6NCOtBu). Complex3is a four-coordinate disphenoidal high-spin Ni(II) complex, excluding short anagostic Ni-tBu hydrogen interactions. Complex3reacts with the paddle-wheel [Ph3PNi(μ-CO2tBu)2]2(6·PPh3) ortBuCO2H to give insoluble {[AQpiv]Ni(O2CtBu)}2(5). Dissolution of5in donor solvents L (L= DMSO and DMF) gave a paramagnetic intermediate assigned by NMR as [AQpiv]Ni(O2CtBu)L (5·L) and equilibrium reformation of3and6·L. DFT calculations support this equilibrium in solution. Both3and5undergo C-H activation at temperatures as low as 80 °C and in the presence of PR3(PR3= PPh3, PiBu3) to give Ni(C9NH6NCOCMe2CH2-κN,N,C)PR3(7·PR3). The C-H functionalization reaction orders with respect to7·PiBu3, iodoarenes, and phosphines were determined. Hammett analysis using electronically different aryl iodides suggests a concerted oxidative addition mechanism for the C-H functionalization step; DFT calculations were also carried out to support this finding. When Na2CO3is used as the base, the rate determination step for C-H functionalization appears to be 8-aminoquinoline deprotonation and binding to Ni. The carbonate anion was also observed to provide a deleterious NMR-inactive low-energy off-cycle resting state in catalysis. Replacement of Na2CO3with NaOtBu improved catalysis at milder conditions and made carboxylic acid and phosphine additives unnecessary. Complex3and its functionalized analogues were observed as the catalyst resting state under these conditions.
