3682-07-3Relevant articles and documents
Crystal-to-Crystal Synthesis of Photocatalytic Metal–Organic Frameworks for Visible-Light Reductive Coupling and Mechanistic Investigations
Bucci, Alberto,Escudero-Adán, Eduardo C.,Gutiérrez, Luis,Kandoth, Noufal,Lloret-Fillol, Julio,Mondal, Suvendu Sekhar,Shafir, Alexandr
, (2020/06/10)
Postmodification of reticular materials with well-defined catalysts is an appealing approach to produce new catalytic functional materials with improved stability and recyclability, but also to study catalysis in confined spaces. A promising strategy to this end is the postfunctionalization of crystalline and robust metal–organic frameworks (MOFs) to exploit the potential of crystal-to-crystal transformations for further characterization of the catalysts. In this regard, two new photocatalytic materials, MOF-520-PC1 and MOF-520-PC2, are straightforwardly obtained by the postfunctionalization of MOF-520 with perylene-3-carboxylic acid (PC1) and perylene-3-butyric acid (PC2). The single crystal-to-crystal transformation yielded the X-ray diffraction structure of catalytic MOF-520-PC2. The well-defined disposition of the perylenes inside the MOF served as suitable model systems to gain insights into the photophysical properties and mechanism by combining steady-state, time-resolved, and transient absorption spectroscopy. The resulting materials are active organophotoredox catalysts in the reductive dimerization of aromatic aldehydes, benzophenones, and imines under mild reaction conditions. Moreover, MOF-520-PC2 can be applied for synthesizing gram-scale quantities of products in continuous-flow conditions under steady-state light irradiation. This work provides an alternative approach for the construction of well-defined, metal-free, MOF-based catalysts.
B2pin2-Mediated Palladium-Catalyzed Diacetoxylation of Aryl Alkenes with O2 as Oxygen Source and Sole Oxidant
Huang, Jiuzhong,Ouyang, Lu,Li, Jianxiao,Zheng, Jia,Yan, Wuxin,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 5090 - 5093 (2018/09/12)
A novel palladium-catalyzed alkene diacetoxylation with dioxygen (O2) as both the sole oxidant and oxygen source is developed, which was identified by 18O-isotope labeling studies. Control experiments suggested that bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation of a C-O bond. This method performed good functional group tolerance with moderate to excellent yields, which could be successfully applied to the late-stage modification of natural products. Furthermore, an atmospheric pressure of dioxygen enhances the practicability of the protocol.
Metal-free reductive coupling of CO and CN bonds driven by visible light: Use of perylene as a simple photoredox catalyst
Okamoto, Shusuke,Kojiyama, Keita,Tsujioka, Hiroki,Sudo, Atsushi
supporting information, p. 11339 - 11342 (2016/09/23)
Perylene, a simple polycyclic aromatic hydrocarbon, was used as a photoredox catalyst to enable the reductive coupling reaction of aromatic aldehydes, ketones, and an imine under visible-light irradiation using a white LED.
Metal-free, organocatalytic syn diacetoxylation of alkenes
Zhong, Wenhe,Liu, Shan,Yang, Jun,Meng, Xiangbao,Li, Zhongjun
supporting information; experimental part, p. 3336 - 3339 (2012/08/29)
A novel method for the organocatalytic syn diacetoxylation of alkenes has been developed using aryl iodides as efficient catalysts. A broad range of substrates, including electron-rich as well as electron-deficient alkenes, are smoothly transformed by the new procedure, furnishing the desired products in good to excellent yields with high diastereoselectivity (up to >19:1 dr).
BF3·OEt2-promoted diastereoselective diacetoxylation of alkenes by PhI(OAc)2
Zhong, Wenhe,Yang, Jun,Meng, Xiangbao,Li, Zhongjun
experimental part, p. 9997 - 10004 (2012/02/05)
Selective syn and anti diacetoxylations of alkenes have been achieved using a PhI(OAc)2/BF3·OEt2 system in the presence and absence of water, respectively. A broad range of substrates including electron-deficient alkenes (such as α,β-unsaturated esters) could be elaborated efficiently at room temperature with this methodology, furnishing the desired products in good to excellent yields and diastereoselectivity. In particular, a multigram-scale diastereoselective diacetoxylation of methyl cinnamate (5.00 g) was also accomplished in a few hours, maintaining the same efficiency as small-scale reaction. This novel methodology provides an alternative approach for the preparation of various 1,2-diols.
Efficient diacetoxylation of alkenes via Pd(II)/Pd(IV) process with peracetic acid and acetic anhydride
Park, Chan Pil,Lee, Joo Ho,Yoo, Kyung Soo,Jung, Kyung Woon
supporting information; experimental part, p. 2450 - 2452 (2010/07/05)
A palladium-catalyzed diacetoxylation of alkenes in the presence of peracetic acid and acetic anhydride was developed to produce diacetates efficiently and diastereoselectively. Due to its mild conditions, this method was suitable for a broad range of substrates encompassing conjugated and nonconjugated olefins.
Bis(NHC)-palladium(II) complex-catalyzed dioxygenation of alkenes
Wang, Wenfeng,Wang, Feijun,Shi, Min
experimental part, p. 928 - 933 (2010/05/01)
Bis(NHC)-Pd(II) complexes derived from l,l'-binaphthyl-2,2'-diamine (BINAM) were successfully first used to catalyze the dioxygenation of alkenes under mild conditions tolerant of air and moisture. Cationic NHC-Pd2+ diaquo complex 1e showed the highest catalytic activity to give 1,2dioxygenation products with good syn-diastereoselectivity for 1,2-disubstituted alkenes.
Palladium-catalyzed olefin dioxygenation
Li, Yang,Song, Datong,Dong, Vy M.
, p. 2962 - 2964 (2008/09/20)
A general method for the vicinal dioxygenation of olefins was developed using cationic Pd diphosphine complexes as the catalysts and PhI(OAc)2 as the terminal oxidant. In comparison to known Pd-catalyzed vicinal oxidations, this method is suitable for a broad range of olefins in both inter- and intramolecular reactions. An 18O-labeling experiment provides insight into the mechanism of this transformation which presumably involves Pd(II)/Pd(IV) intermediates. Copyright
Reductive esterification of aromatic aldehydes using Zn/Ac 2O/imidazole or Zn/Yb(OTf)3/(RCO)2O system
Hirao, Toshikazu,Santhitikul, Sirida,Takeuchi, Hiroki,Ogawa, Akiya,Sakurai, Hidehiro
, p. 10147 - 10152 (2007/10/03)
Benzaldehydes are reduced by metallic zinc in the presence of Ac 2O and imidazole, giving the corresponding benzyl acetates in good yields. Reductive esterification of aromatic aldehydes is also carried out via gem-diacetoxy compounds. Carbonyl compounds are readily converted to the gem-diacyloxy compounds in excellent yields on treatment with 2molar amounts of acid anhydride and 10mol% of Yb(OTf)3 in MeCN at room temperature. Thus-formed diacyloxy compounds derived from aromatic aldehydes are reduced in situ by metallic zinc to afford the corresponding esters.