14171-88-1Relevant articles and documents
Generation of Alkyl Radicals from 1-Oxidoalkylidenechromium(0) Complexes by Oxidation with Manganese(III) 2-Pyridinecarboxylate and Their Reactions with Olefins
Narasaka, Koichi,Sakurai, Hidehiro
, p. 1269 - 1272 (1993)
Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chromium(0) complexes, prepared from the corresponding carbanion and hexacarbonylchromium(0), are oxidized with manganese(III) 2-pyridinecarboxylate to generate carbon-centered radicals which react with various olefins giving the intermolecular addition products.
Oxidation and β-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands
Jiménez, M. Victoria,Fernández-Tornos, Javier,Modrego, F. Javier,Pérez-Torrente, Jesús J.,Oro, Luis A.
supporting information, p. 17877 - 17889 (2015/12/08)
The borrowing hydrogen methodology allows for the use of alcohols as alkylating agents for C-C bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)-cyclooctadiene complexes having a NHC ligand with a O- or N-functionalised wingtip efficiently catalysed the oxidation and β-alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3)(cod)(MeIm(2- methoxybenzyl))][BF4] (cod=1,5-cyclooctadiene, MeIm=1-methylimidazolyl) having a rigid O-functionalised wingtip, shows the best catalyst performance in the dehydrogenation of benzyl alcohol in acetone, with an initial turnover frequency (TOF0) of 1283 h-1, and also in the β-alkylation of 2-propanol with butan-1-ol, which gives a conversion of 94 % in 10 h with a selectivity of 99 % for heptan-2-ol. We have investigated the full reaction mechanism including the dehydrogenation, the cross-aldol condensation and the hydrogenation step by DFT calculations. Interestingly, these studies revealed the participation of the iridium catalyst in the key step leading to the formation of the new C-C bond that involves the reaction of an O-bound enolate generated in the basic medium with the electrophilic aldehyde.
Borohydride-mediated radical addition reactions of organic iodides to electron-deficient alkenes
Kawamoto, Takuji,Uehara, Shohei,Hirao, Hidefumi,Fukuyama, Takahide,Matsubara, Hiroshi,Ryu, Ilhyong
, p. 3999 - 4007 (2014/05/20)
Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tin reagents, the reaction took place chemoselectively at the carbon-iodine bond but not at the carbon-bromine or carbon-chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant for the hydrogen abstraction of a primary alkyl radical from tetrabutylammonium cyanoborohydride was estimated to be 4 M-1 s-1 at 25 °C by a kinetic competition method. This value is 3 orders of magnitude smaller than that of tributyltin hydride.
Temporal separation of catalytic activities allows anti-Markovnikov reductive functionalization of terminal alkynes
Li, Le,Herzon, Seth B.
, p. 22 - 27 (2014/01/17)
There is currently great interest in the development of multistep catalytic processes in which one or several catalysts act sequentially to rapidly build complex molecular structures. Many enzymes - often the inspiration for new synthetic transformations - are capable of processing a single substrate through a chain of discrete, mechanistically distinct catalytic steps. Here, we describe an approach to emulate the efficiency of these natural reaction cascades within a synthetic catalyst by the temporal separation of catalytic activities. In this approach, a single catalyst exhibits multiple catalytic activities sequentially, allowing for the efficient processing of a substrate through a cascade pathway. Application of this design strategy has led to the development of a method to effect the anti-Markovnikov (linear-selective) reductive functionalization of terminal alkynes. The strategy of temporal separation may facilitate the development of other efficient synthetic reaction cascades.
Synthesis and DHFR inhibitory activity of a series of 6-substituted-2,4-diaminothieno[2,3-d]pyrimidines
Donkor, Isaac O.,Li, Hui,Queener, Sherry F.
, p. 605 - 611 (2007/10/03)
A series of 6-aralkyl substituted 2,4-diaminothieno[2,3-d]pyrimidines in which the 6-aryl group is separated from the thieno[2,3-d]pyrimidine ring by two to five methylene groups were synthesized and studied as inhibitors of dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, Mycobacterium avium, and rat liver. Compounds in which the thieno[2,3-d]pyrimidine ring is separated from the 6-aryl substituent by three methylene groups were the most potent inhibitors of the series (with IC50 values ranging from 0.24 and 11.0 μM) but those with two methylene groups between the aromatic rings were the most selective agents.
Indirect Electroreductive Addition of Alkyl Radicals to Activated Olefins using a Nickel(II) Complex as an Electron-transfer Catalyst
Ozaki, Shigeko,Matsushita, Hidenori,Ohmori, Hidenobu
, p. 649 - 652 (2007/10/02)
Indirect electroreductive intermolecular addition of primary and secondary alkyl radicals has been achieved using a nickel(II) complex as an electron-transfer catalyst.
