4453-79-6Relevant articles and documents
Deprotection of benzylic esters catalysed by anhydrous ferric chloride and rhenium carbonyl compounds
Davies, Timothy J.,Jones, Ray V.H.,Lindsell, W.Edward,Miln, Colin,Preston, Peter N.
, p. 487 - 488 (2002)
Anhydrous ferric chloride and [Re(CO)4Br]2 are shown to be useful reagents for the catalytic deprotection of benzylic esters. A suitable protecting group is p-MeC6H4CH2 with a working temperature of 5
A new layered MWW zeolite synthesized with the bifunctional surfactant template and the updated classification of layered zeolite forms obtained by direct synthesis
Grzybek, Justyna,Roth, Wieslaw J.,Gil, Barbara,Korzeniowska, Aleksandra,Mazur, Michal,?ejka, Ji?i,Morris, Russell E.
, p. 7701 - 7709 (2019)
The medium pore-size zeolite MWW is very valuable as an industrial catalyst for aromatic alkylation and the first zeolite identified in the layered form. It shows extraordinary diversity by producing a great variety of different layered structures and forms: so far about 15 obtained by direct preparation and post-synthesis modifications, with 18 altogether recognised for all layered zeolites. We report a new layered MWW material, denoted UJM-1P (Uniwersytet Jagiellonski Material #1), which was obtained by prolonging synthesis of the mono-layered MWW material reported earlier, MIT-1. This transformation is new but not totally surprising. MIT-1 was obtained by using a special bifunctional structure directing agent (SDA) containing adamantyl head group and a long hydrocarbon chain. This strategy was applied first to produce by design layered forms of one of the most important zeolites-MFI. The MWW framework was previously obtained by direct synthesis in 5 different forms that could be rationalized by particular layer arrangements. MFI added 3 more types with two prepared, before MIT-1, with the aforementioned bifunctional SDA. MIT-1 and UJM-1P (as synthesized) and UJM-1 (calcined) are analogues of these layered MFI materials and are considered as the 6th and 7th MWW forms obtained by a direct one-pot preparation. UJM-1P has a multilayered slightly expanded structure similar to MCM-22P by with extensive layer disorder. It is easier to swell with surfactants than MCM-22P, which indicates weak interlayer connection that may be due to the special SDA molecules lining the surface of its layers. This is promising for delamination and formation of colloidal dispersions of MWW mono-layers. UJM-1 was confirmed to be a very active solid acid catalyst showing high concentration of Br?nsted acid sites of about 900 μmol g?1. It was tested in the mesitylene alkylation reaction showing high activity comparable to MCM-56, while MIT-1 was about 50% less active.
Cascade Reductive Friedel-Crafts Alkylation Catalyzed by Robust Iridium(III) Hydride Complexes Containing a Protic Triazolylidene Ligand
Albrecht, Martin,Alshakova, Iryna D.
, p. 8999 - 9007 (2021/07/31)
The synthesis of complex molecules like active pharmaceutical ingredients typically requires multiple single-step reactions, in series or in a modular fashion, with laborious purification and potentially unstable intermediates. Cascade processes offer attractive synthetic remediation as they reduce time, energy, and waste associated with multistep syntheses. For example, triarylmethanes are traditionally prepared via several synthetic steps, and only a handful of cascade routes are known with limitations due to high catalyst loadings. Here, we present an expedient catalytic cascade process to produce triarylmethanes. For this purpose, we have developed a bifunctional iridium system as the efficient catalyst to build heterotriaryl synthons via reductive Friedel-Crafts alkylation from ketones, arenes, and hydrogen. The catalytically active species were generated in situ from a robust triazolyl iridium(III) hydride complex and acid and is composed of a metal-bound hydride and a proximal ligand-bound proton for reversible dihydrogen release. These complexes catalyze the direct hydrogenation of ketones at slow rates followed by dehydration. Appropriate adjustment of the conditions successfully intercepts this dehydration and leads instead to efficient C-C coupling and Friedel-Crafts alkylation. The scope of this cascade process includes a variety of carbonyl substrates such as aldehydes, (alkyl)(aryl)ketones, and diaryl ketones as precursor electrophiles with arenes and heteroarenes for Friedel-Crafts coupling. The reported method has been validated in a swift one-step synthesis of the core structure of a potent antibacterial agent. Excellent yields and exquisite selectivities were achieved for this cascade process with unprecedentedly low iridium loadings (0.02 mol %). Moreover, the catalytic activity of the protic system is significantly higher than that of an N-methylated analogue, confirming the benefit of the Ir-H/N-H hydride-proton system for high catalytic performance.
Preparation method of diarylmethane and derivatives thereof
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Paragraph 0054-0057, (2021/04/21)
The invention discloses a preparation method of a diarylmethane compound and a derivative thereof. In a protective atmosphere, heating reaction is carried out on aryl aldehyde and an aromatic hydrocarbon compound in the presence of phosphorous acid and elemental iodine to obtain diarylmethane and the derivative thereof. According to the method, cheap and green solid phosphorous acid is selected as a reducing reagent and an accelerant for reaction, the diarylmethane and the derivative thereof are efficiently prepared by a one-pot one-step method starting from a simple and easily available aryl aldehyde compound in the presence of elemental iodine, and the method has the advantages of simplicity in operation, cheap and easily available reagents, environmental friendliness and the like; use of expensive reducing reagents, metal reagents and transition metal catalysts is avoided, and industrial production is facilitated.
