1027335-55-2Relevant articles and documents
Ruthenium-mediated C-H functionalization of pyridine: The role of vinylidene and pyridylidene ligands
Johnson, David G.,Lynam, Jason M.,Mistry, Neetisha S.,Slattery, John M.,Thatcher, Robert J.,Whitwood, Adrian C.
, p. 2222 - 2234 (2013)
A combined experimental and theoretical study has demonstrated that [Ru(η5-C5H5)(py)2(PPh 3)]+ is a key intermediate, and active catalyst for, the formation of 2-substituted E-styrylpyridines from pyridine and terminal alkynes HC - CR (R = Ph, C6H4-4-CF3) in a 100% atom efficient manner under mild conditions. A catalyst deactivation pathway involving formation of the pyridylidene-containing complex [Ru(η 5-C5H5)(κ3-C 3-C5H4NCH=CHR)(PPh3)]+ and subsequently a 1-ruthanaindolizine complex has been identified. Mechanistic studies using 13C- and D-labeling and DFT calculations suggest that a vinylidene-containing intermediate [Ru(η5-C5H 5)(py)(=C=CHR)(PPh3)]+ is formed, which can then proceed to the pyridylidene-containing deactivation product or the desired product depending on the reaction conditions. Nucleophilic attack by free pyridine at the α-carbon in this complex subsequently leads to formation of a C-H agostic complex that is the branching point for the productive and unproductive pathways. The formation of the desired products relies on C-H bond cleavage from this agostic complex in the presence of free pyridine to give the pyridyl complex [Ru(η5-C5H5)(C 5H4N)(=C=CHR)(PPh3)]. Migration of the pyridyl ligand (or its pyridylidene tautomer) to the α-carbon of the vinylidene, followed by protonation, results in the formation of the 2-styrylpyridine. These studies demonstrate that pyridylidene ligands play an important role in both the productive and nonproductive pathways in this catalyst system.
Determination and application of the excited-state substituent constants of pyridyl and substituted phenyl groups
Cao, Chao-Tun,Yan, Lu,Cao, Chenzhong
, (2021/05/21)
Thirty six 1-pyridyl-2-arylethenes XCH=CHArY (abbreviated XAEY) were synthesized, in which, X is 2-pyridyl, 3-pyridyl and 4-pyridyl and Y is OMe, Me, H, Br, Cl, F, CF3, and CN. Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelengths of absorption maximum λmax were recorded. Also, the 234 λmax values of 1-substituted phenyl-2-arylethylene compounds (XAEY, where X is substituted phenyl) were collected. The excited-state substituent constants (Formula presented.) of three pyridyl groups and 23 substituted phenyl groups (total of 26) were obtained by means of curve-fitting method. Taking the λmax values of 358 samples of bi-arylethene derivatives as a data set and 126 samples of bi-aryl Schiff bases (including nine compounds synthesized by this work) as another data set, quantitative correlation analyses were performed by employing the obtained (Formula presented.) as a parameter, and good results were obtained for the two data sets. The reliability of the obtained (Formula presented.) values was verified. The results of this paper can provide excited-state substituent constants for the study and application of optical properties of conjugated organic compounds containing aryl groups.
Heck cross-coupling of vinyl heteroaromatic compounds with aryl and heteroaryl halides using Pd(II) complex under phosphine-free conditions
Annapurna, Manne,Vishnuvardhan Reddy,Singh, Surya Prakash,Kantam, Mannepalli Lakshmi
, p. 10940 - 10945 (2014/01/06)
The palladium-catalyzed cross-coupling reaction of vinyl heteroaromatic compounds with aryl bromides and heteroaryl bromides is described using air and moisture stable N,N′,N″,O-tetrafunctional Pd catalyst under phosphine-free conditions. As a result a variety of trans-1,2-disubstituted vinyl heterocycles were obtained in high to good yields.
