6626-32-0Relevant articles and documents
Cobalt-Nitrenoid Insertion-Mediated Amidative Carbon Rearrangement via Alkyl-Walking on Arenes
Lee, Jeonghyo,Kang, Bora,Kim, Dongwook,Lee, Jia,Chang, Sukbok
supporting information, p. 18406 - 18412 (2021/11/16)
We herein disclose the Cp*Co(III)(LX)-catalyzed amidative alkyl migration using 2,6-disubstituted phenyl azidoformates. Upon the cobalt-nitrenoid insertion toward the substituted ortho carbon, an arenium cationic species bearing a quaternary carbon is generated, and a subsequent alkyl migration process is suggested to occur through an unforeseen alkyl-walking mechanism. A quinolinol ligand of the cobalt catalyst system is proposed to facilitate the final product-releasing rearomatization process by serving as an internal base. This new mechanistic mode enabled both [1,2]- and [1,4]-alkyl rearrangements to allow the structural variation of N-heterocyclic compounds.
Ortho-selective alkylation of phenol with 1-propanol catalyzed by CeO2-MgO
Sato, Satoshi,Takahashi, Ryoji,Sodesawa, Toshiaki,Matsumoto, Kotaro,Kamimura, Yoichiro
, p. 180 - 188 (2007/10/03)
Vapor-phase alkylation of phenol with 1-propanol was investigated over CeO2-MgO catalysts prepared utilizing a molten mixture of the corresponding nitrates and citric acid. The CeO2-MgO had a stable catalytic activity at 475°C, and had an excellent selectivity to 2-propylphenol, higher than 82% based on phenol. Although a portion of the 2-propylphenol produced was decomposed into o-cresol and 2-ethylphenol, a sum of selectivities to the monoalkylated phenols exceeded 97%. During the alkylation, propanal and 3-pentanone was observed. In the results of 1-propanol conversion without phenol, it was found that 1-propanol was dehydrogenated to propanal and that the propanal produced was dimerized to 3-hydroxy-2-methylpentanal via aldol addition, followed by the deformylation into 3-pentanone. Namely, in the reaction of phenol and 1-propanol, the propylation of phenol and the dehydrogenation of 1-propanol occurred concurrently over the CeO2-MgO. The pure CeO2, having both the redox property with Ce4+-Ce3+ and weak basic sites, catalyzed both the propylation of phenol and the 1-propanol transformation into 3-pentanone, while the pure MgO with strong basicity was less active for the 1-propanol transformation and had a low reaction rate in the alkylation. The reaction mechanism of the ortho-propylation over the CeO2-MgO catalyst is speculated as follows. The ortho position of phenol adsorbed perpendicularly on weak basic sites of the catalyst is selectively alkylated by 1-propanol, which is possibly activated in the form of 1-hydroxypropyl radical on CeO2 species rather than as a form of n-propyl cation. The redox property of CeO2 is probably attributed to the homolitic activation of 1-propanol to produce 1-hydroxypropyl radical.
Alumina-Catalyzed Reactions of Hydroxyarenes and Hydroaromatic Ketones. 9. Reaction of Phenol with 1-Propanol
Klemm, LeRoy H.,Taylor, Dennis R.
, p. 4320 - 4326 (2007/10/02)
At 250-350 deg C in the presence of alumina, phenol (1) reacts with excess 1-propanol to give mainly (>90percent) C-alkylation to form mono- to penta-n-propylphenols plus some O-alkylations to form n-propyl aryl ethers. The principal component of the product mixture from 1 is 2,6-di-n-propylphenol (26-50 mol percent yield). With 4-n-propylphenol as substrate (instead of 1), tri-, tetra-, and penta-n-propylphenols are formed in 48-79percent combined yield. On the average, only 3percent of the total C3H7 groups in the product mixture are isopropyl ones. Deoxygenation is not observed. It is proposed that the principal products result from an SN2-type reaction mechanism which involves nucleophilic attack (variously by C-2, C-4, C-6, or O) of an adsorbed ambident phenoxide ion onto C-1 of an adsorbed n-propoxide group. n-Propylation at C-3 and C-5 of the phenol ring results from surface-catalyzed dienone-phenol rearrangement.Isopropylation may occur via a side reaction of SN1 type.
