881-07-2Relevant articles and documents
Planar-locked Ru-PNN catalysts in 1-phenylethanol dehydrogenation
Fanara, Paul M.,MacMillan, Samantha N.,Lacy, David C.
, p. 3628 - 3644 (2020/11/03)
Ru-PNN pincer catalysts of the general form [{PNN}Ru(H)(Cl)(CO)] can dehydrogenate alcohols through inner- and outer-sphere mechanisms, but determining the favored path is challenging. To address this challenge, the following planar-locked quinoline-based PNN ligands, which cannot form key inner-sphere transition states and intermediates, were synthesized: 2-((ditertbutylphosphaneyl)methyl)-N,N-diethylquinolin-8-amine (QNPtBu), 2-((diisopropylphosphaneyl)methyl)-N,N-diethyl-quinolin-8-amine (QNPiPr), and 2-((diphenylphosphaneyl)-methyl)-N,N-diethylquinolin-8-amine (QNPPh). In addition to the quinoline-derived ligands, we also prepared the isoquinoline PNN ligand N-((1-((ditert-butylphosphaneyl)methyl)isoquinolin-3-yl)methyl)-N-ethylethanamine (IsoQNP) and two known picoline- and lutidine-derived ligands 2-((ditert-butylphosphaneyl)-methyl)pyridine (PicP) and 2-((ditert-butylphosphaneyl)methyl)-6-methylpyridine (LutP). These six ligands were coordinated to Ru(II) ions to prepare six new complexes of the general formulation [{L}Ru(H)(Cl)(CO)] analogous to Milstein’s PNN catalyst precursor (1PyCl). The X-ray structural, NMR, UV-vis, and FTIR spectroscopic properties of the new complexes are similar to parent complex 1PyCl and were used in catalytic 1-phenylethanol acceptor-less and transfer dehydrogenation. The comparative results demonstrate that 1Py outperforms the other catalysts. DFT reaction profiles were computed for 1Py and the planar-locked catalysts. The results suggest that 1Py has access to a lower-energy inner-sphere path, whereas the planar-locked catalysts can only proceed through a high-energy outer-sphere mechanism and may even get trapped in unreactive alkoxide sinks.
Approach to the synthesis of 8-nitroquinoline-2-carboxylic acid in high yield
Gadomsky, S. Ya.,Yakuschenko
, p. 816 - 818 (2016/12/27)
A synthesis of 8-nitroquinoline-2-carboxylic acid was optimized, using the following basic scheme of transformations: 1) nitration of 2-methylquinoline with subsequent separation of a mixture of isomeric 8-nitroand 5-nitro-2-methylquinolines; 2) oxidation of the methyl group in 2-methyl-8-nitroquinoline (including consecutive steps of bromination and hydrolysis in aqueous sulfuric acid). A new method for the separation of isomeric 8-nitroand 5-nitro-2methylquinolines was suggested. The optimal conditions for the final step of hydrolysis were selected, which gave almost quantitative yield of 8-nitroquinoline-2-carboxylic acid.
Substitution effect on the one- and two-photon sensitivity of DMAQ "caging" groups
Petit, Morgane,Tran, Christine,Roger, Thomas,Gallavardin, Thibault,Dhimane, Hamid,Palma-Cerda, Francisco,Blanchard-Desce, Mireille,Acher, Francine C.,Ogden, David,Dalko, Peter I.
supporting information, p. 6366 - 6369 (2013/02/23)
The systematic SAR study of a "caging" group showed a strong influence of the position of the donor dimethylamino group on the efficiency of photolysis of the DMAQ (2-hydroxymethylene-(N,N-dimethylamino)quinoline) caged acetate under one-photon near-UV or two-photon near-IR excitation. Photorelease of l-glutamate by the most efficient 8-DMAQ derivative strongly and efficiently activated glutamate receptors, generating large, fast rising responses similar to those elicited by glutamate photoreleased from the widely used MNI-caged glutamate.