- Alumina grafted SBA-15 sustainable bifunctional catalysts for direct cross-coupling of benzylic alcohols to diarylmethanes
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AlSBA-15 catalysts possessing Br?nsted acid and Lewis acid-base bifunctionalities catalyze the direct arylation of benzyl alcohols to diarylmethanes with an 85% product yield through C-O bond activation. 2 and 4wt%AlSBA-15 catalysts have been synthesised by adopting a simple and efficient post-synthetic metal implantation route. The synthesised catalysts were characterized using XRD, N2 adsorption and desorption, 27Al MAS NMR, XPS, HR-TEM, NH3 and CO2-temperature-programmed desorption (TPD) and pyridine-transmission-FTIR spectroscopy techniques to confirm the existence of Br?nsted acid and Lewis acid-base bifunctionalities. Through various control experiments, it is verified that Br?nsted acid sites activate the benzyl alcohol and Lewis base sites interact with phenylboronic acid concurrently to accomplish the coupling reaction. In the recyclability study, 4wt%AlSBA-15 preserves its activity and stability up to 5 cycles. The 4wt%AlSBA-15 catalyst unlike homogeneous catalysts does not require additives, long reaction time and expensive metals.
- Rajendran, Chandran,Satishkumar, Govindaswamy,Lang, Charlotte,Gaigneaux, Eric M.
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p. 2583 - 2592
(2020/05/14)
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- Friedel-crafts benzylation of activated and deactivated arenes
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NO going back makes possible facile Friedel-Crafts benzylations with moderate reaction temperatures, simple reaction workups, and improved substrate scope for the formation of synthetically important diarylmethanes (see scheme). Upon complexation with BF3?OEt2, hydroxamates serve as reversible leaving groups that stabilize highly reactive carbocations. Even deactivated arenes and electron-deficient benzylhydroxamates react cleanly under these conditions.
- Schaefer, Gabriel,Bode, Jeffrey W.
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supporting information; experimental part
p. 10913 - 10916
(2012/01/02)
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- Palladium-catalyzed synthesis of diarylmethanes: Exploitation of carbanionic leaving groups
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A novel route to the synthesis of diarylmethanes via a Pd-catalyzed α-arylation of benzyl ketones is rseported. By harnessing the inherent reactivity of enolates, it is possible to circumvent the need for a transmetalating reagent such as boron for the co
- Schmink, Jason R.,Leadbeater, Nicholas E.
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supporting information; experimental part
p. 2575 - 2578
(2009/10/02)
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- Cross-coupling reactions with boronic acids in water catalysed by oxime-derived palladacycles
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Palladacycles derived from phenone-oximes 1 are efficient precatalysts for the Suzuki-Miyaura coupling of arylboronic acids with aromatic and heteroaromatic bromides and chlorides under water reflux under aerobic conditions. Alternatively, the coupling can also be carried out at room temperature in methanol-water. Aryl bromides gave biaryls with TON up to 105 and TOF up to 7 × 104 h-1. Activated and deactivated aryl chlorides need the presence of TBAB for the couplings, showing slightly lower efficiency (TON up to 9000 and TOF up to 3850 h-1). C(sp2)-C(sp3) bonds can also be formed by cross-coupling reactions of trimethylboroxine and butylboronic acid with aromatic bromides and chlorides under water reflux and of benzylic and allylic chlorides or acetates with arylboronic acids in acetone-water at room temperature.
- Botella, Luis,Nájera, Carmen
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- Preparation process of fluorine substituted aromatic compound
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A preparation process of a fluorine substituted aromatic compound comprising reacting an alkali metal or alkali earth metal salt of an aromatic compound having a hydroxy group with an organic fluorinating agent is disclosed. As a representative fluorinating agent, a bis-dialkylamino-difluoromethane compound, for example, 2,2′-difluoro-1,3-dimethylimidazolidine, is exemplified. According to the process, an industrially useful fluorinated aromatic compound, for example, a fluorobenzene, a fluorine substituted benzophenone, a fluorine substituted diarylsulfone can be prepared with ease in economy without specific equipment.
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