95-48-7Relevant articles and documents
Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds
Martos, Mario,Pastor, Isidro M.
, (2022/01/03)
Different carboxy-functionalized imidazolium salts have been considered as components of low transition temperature mixtures (LTTMs) in combination with urea. Among them, a novel LTTM based on 1-(methoxycarbonyl)methyl-3-methylimidazolium chloride and urea has been prepared and characterized by differential scanning calorimetry throughout its entire composition range. This LTTM has been employed for the oxidation of boron reagents using urea-hydrogen peroxide adduct (UHP) as the oxidizer, thus avoiding the use of aqueous H2O2, which is dangerous to handle. This metal-free protocol affords the corresponding alcohols in good to quantitative yields in up to 5 mmol scale without the need of further purification. The broad composition range of the LTTM allows for the reaction to be carried out up to three consecutive times with a single imidazolium salt loading offering remarkable sustainability with an E-factor of 7.9, which can be reduced to 3.2 by the threefold reuse of the system.
Catalytic Activation of Unstrained C(Aryl)-C(Alkyl) Bonds in 2,2′-Methylenediphenols
Dong, Guangbin,Ratchford, Benjamin L.,Xue, Yibin,Zhang, Rui,Zhu, Jun
supporting information, p. 3242 - 3249 (2022/02/23)
Catalytic activation of unstrained and nonpolar C-C bonds remains a largely unmet challenge. Here, we describe our detailed efforts in developing a rhodium-catalyzed hydrogenolysis of unstrained C(aryl)-C(alkyl) bonds in 2,2′-methylenediphenols aided by removable directing groups. Good yields of the monophenol products are obtained with tolerating a wide range of functional groups. In addition, the reaction is scalable, and the catalyst loading can be reduced to as low as 0.5 mol %. Moreover, this method proves to be effective to cleave C(aryl)-C(alkyl) linkages in both models of phenolic resins and commercial novolacs resins. Finally, detailed experimental and computational mechanistic studies show that with C-H activation being a competitive but reversible off-cycle reaction, this transformation goes through a directed C(aryl)-C(alkyl) oxidative addition pathway.
Visible light-induced photodeoxygenation of polycyclic selenophene Se-oxides
Chintala, Satyanarayana M.,Throgmorton, John C.,Maness, Peter F.,McCulla, Ryan D.
, (2020/10/02)
Photodeoxygenation of dibenzothiophene S-oxide (DBTO) is believed to produce ground-state atomic oxygen [O(3P)] in solution. Compared with other reactive oxygen species (ROS), O(3P) is a unique oxidant as it is potent and selective. Derivatives of DBTO have been used as O(3P)-precursors to oxidize variety of molecules, including plasmid DNA, proteins, lipids, thiols, and other small organic molecules. Unfortunately, the photodeoxygenation of DBTO requires ultraviolet irradiation, which is not an ideal wavelength range for biological systems, and has a low quantum yield of approximately 0.003. In this work, benzo[b]naphtho[1,2-d]selenophene Se-oxide, benzo[b]naphtho[2,1-d]selenophene Se-oxide, dinaphtho[2,3-b:2’,3’-d]selenophene Se-oxide, and perylo[1,12-b,c,d]selenophene Se-oxide were synthesized, and their ability to utilize visible light for generating O(3P) was interrogated. Benzo[b]naphtho[1,2-d]selenophene Se-oxide produces O(3P) upon irradiation centered at 420 nm. Additionally, benzo[b]naphtho[1,2-d]selenophene Se-oxide, benzo[b]naphtho[2,1-d]selenophene Se-oxide, and dinaphtho[2,3-b:2’,3’-d]selenophene Se-oxide produce O(3P) when irradiated with UVA light and have quantum yields of photodeoxygenation ranging from 0.009 to 0.33. This work increases the utility of photodeoxygenation by extending the range of wavelengths that can be used to generate O(3P) in solution.