- Synthesis and properties of benzophenone-spiropyran and naphthalene-spiropyran conjugates
-
We have designed and synthesized four compounds integrating luminescent and photochromic components in their molecular skeletons. Two of them combine a nitrospiropyran photochrome with either one or two naphthalene fluorophores and can be prepared in three synthetic steps. The other two consist of a nitrospiropyran photochrome and a benzophenone phosphore connected by either ether or ester linkages and can be prepared in six or five, respectively, synthetic steps. The luminescent components of these assemblies are expected to transfer energy intramolecularly to the photochromic species upon excitation and encourage their photoisomerization. Consistently, the phosphorescence of the benzophenone units and the fluorescence of the naphthalene components are effectively quenched when these species are connected covalently to a nitrospiropyran. Nonetheless, the photoisomerization of the photochrome becomes significantly less efficient after the covalent attachment to the luminescent partner. The fraction of incident radiations absorbed by either the benzophenone or the naphthalene fragment does not promote the isomerization of the photochromic appendage. Instead, irreversible transformations occur upon irradiation of the luminophore-photochrome assemblies. Thus, the covalent attachment of a benzophenone or a naphthalene to a nitrospiropyran is not a viable strategy to improve the photocoloration efficiency of the photochromic component. Even although the very same luminophores are known to sensitize intermolecularly the isomerization of nitrospiropyrans, the transition to covalent luminophore-photochrome assemblies tends to promote degradation, rather than sensitization, upon irradiation.
- Tomasulo, Massimiliano,Kaanumal, Sireesha L.,Sortino, Salvatore,Raymo, Francisco M.
-
-
Read Online
- Ruthenium-Catalyzed Dehydrogenation of Alcohols with Carbodiimide via a Hydrogen Transfer Mechanism
-
Ruthenium-catalyzed oxidative dehydrogenation of alcohols using carbodiimide as an efficient hydrogen acceptor has been developed. The protocol exhibits wide substrate scope with good to excellent yields. The results of the kinetic analysis indicated that the reaction mechanism includes the hydrogen transfer process and that the addition of carbodiimide is essential for the reaction system, and the resulting amidine also could react as a hydrogen acceptor.
- Sueki, Shunsuke,Matsuyama, Mizuki,Watanabe, Azumi,Kanemaki, Arata,Katakawa, Kazuaki,Anada, Masahiro
-
p. 4878 - 4885
(2020/06/02)
-
- Synthesis of unsymmetrical ketones by applying visible-light benzophenone/nickel dual catalysis for direct benzylic acylation
-
Herein, we report a dual catalytic system for the direct benzylic C-H acylation reaction furnishing a variety of unsymmetrical ketones. A benzophenone-derived photosensitizer combined with a nickel catalyst has been established as the catalytic system. Both acid chlorides and anhydrides are able to acylate the benzylic position of toluene and other methylbenzenes. The method offers a valuable alternative to late transition metal catalyzed C-H acylation reactions.
- Krach, Patricia E.,Dewanji, Abhishek,Yuan, Tingting,Rueping, Magnus
-
supporting information
p. 6082 - 6085
(2020/06/18)
-
- Palladium Catalyzed Direct Acylation of Iodo-Acetanilides/Iodo-Phenyl Acetates: Domino One-Pot Synthesis of 2-Quinolinones
-
Pd-catalyzed direct acylation reaction of iodoacetanilides/iodophenyl acetates with aldehydes is presented. Simple, bench-top aldehydes were used as non-toxic acylating agents. This protocol comprises direct coupling with aldehydes without activating the carbonyl group and without directing group assistance. The strategy was applied to a domino one-pot synthesis of 2-quinolinones through acylation and intramolecular aldol condensation. Significantly, the strategy was extended to the domino one-pot synthesis of drugs and bioactive compounds.
- Basuli, Scuhand,Satyanarayana, Gedu
-
p. 957 - 970
(2017/12/07)
-
- Ligand-free Pd/Cu-catalyzed decarboxylative coupling of aryl iodides with α-oxocarboxylates
-
This paper describes a palladium/copper-catalyzed decarboxylative coupling of aryl iodides with α-oxocarboxylates. The cross-coupling reaction gives high chemical yields of aryl ketones and has wide functional group tolerance, making the transformation an attractive alternative to the traditional cross-coupling approaches for aryl ketones. Copyright
- Ji, Yongfeng,Yang, Xiaomin,Mao, Weixi
-
p. 678 - 680
(2014/09/29)
-
- Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation
-
Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields (see scheme). In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.
- Meng, Li,Su, Jihu,Zha, Zhenggen,Zhang, Li,Zhang, Zhenlei,Wang, Zhiyong
-
supporting information
p. 5542 - 5545
(2013/05/23)
-
- A metal-free catalytic system for the oxidation of benzylic methylenes and primary amines under solvent-free conditions
-
Iodine-pyridine-tert-butylhydroperoxide is developed as a green and efficient catalytic system for the oxidation of benzylic methylenes to ketones and primary amines to nitriles. The reaction conditions are quite mild and environmentally benign, no transition metals, organic solvents or hazard reagents being needed. The oxidation of benzylic methylenes gave the corresponding ketones in excellent yields with complete chemoselectivity, while the oxidation of primary amines was complete in several minutes, affording various nitriles in moderate to good yields.
- Zhang, Jintang,Wang, Zhentao,Wang, Ye,Wan, Changfeng,Zheng, Xiaoqi,Wang, Zhiyong
-
scheme or table
p. 1973 - 1978
(2010/06/15)
-
- Microwave thermolysis - Part IX: A selective and rapid oxidation of benzylic alcohols using clay supported ammonium nitrate
-
The oxidation of a variety of benzylic alcohols to carbonyl compounds using clay-supported ammonium nitrate "clayan" under microwave irradiation is described. The selectivity and non-solvent condition are the important features of the procedure.
- Meshram,Muralidhar,Eeshwaraiah,Babu, K. Ramesh,Aravind,Yadav
-
p. 500 - 502
(2007/10/03)
-
- Cationic palladium(II)-catalyzed addition of arylboronic acids to nitriles. One-step synthesis of benzofurans from phenoxyacetonitriles
-
(Chemical Equation Presented) A cationic palladium complex catalyzed addition of arylboronic acids to nitrites to yield aryl ketones with moderate to good yields was developed. A one-step synthesis of benzofurans from phenoxyacetonitriles under the catalysis of [(bpy)Pd+(μ-OH)] 2(-OTf)2 or [(bpy)Pd2+(H 2O2)2](-OTf)2 was developed which showed that the cationic palladium catalyst is highly active for these addition reactions.
- Zhao, Baowei,Lu, Xiyan
-
p. 5987 - 5990
(2007/10/03)
-
- Infrared and Nuclear Magnetic Resonance Properties of Benzoyl Derivatives of Five-membered Monoheterocycles and Determination of Aromaticity Indices
-
Benzophenones, 2-benzoylthiophenes, 2-benzoylpyrroles, and 2-benzoylfurans, which have substituents at m- and p-positions of the benzoyl ring were prepared and their ir and nmr spectra were obtained in 0.1 M chloroform-d solution. The chemical shift values of each series were plotted against the Hammett substituent parameters to give good correlation, with the exception of the ortho-Hs and -Cs. The slopes as well as the differences in chemical shift gave sets of meaningful values for the indices of aromaticy.
- Jeon, Kyu Ok,Jun, Jung Ho,Yu, Ji Sook,Lee, Chang Kiu
-
p. 763 - 771
(2007/10/03)
-
- (Acyloxy)benzophenones and (Acyloxy)-4-pyrones. A New Class of Inhibitors of Human Neutrophil Elastase
-
A series of 4-(acyloxy)- and 4,4'-bis(acyloxy)benzophenones were synthesized.Some of them, pivalates (trimethylacetates) and isobutyrates in particular, were found to be potent and selective inhibitors of human neutrophil (leukocyte) elastase.A series of 2--5-(acyloxy)-4-pyrones were synthesized regioselectively from kojic acid.The 4-pyrones bearing a long chain acyl group at the 2-position and either pivaloyloxy or isobutyryloxy at the 5-position were potent and selective inhibitors of the human elastase.A number of analogues and derivatives in both series were synthesized in order to study the structure-activity relationship as summarized in Tables I-VI and in Tables IX and X.The inhibition was selective to human neutrophil elastase.No inhibition of porcine pancreatic elastase or bovine pancreatic chymotrypsin (Tables VII and XI) was observed.The most likely mechanism of inhibition is discussed.The implication of these findings for the treatment of rheumatoid arthritis and emphysema is outlined.
- Miyano, Masateru,Deason, James R.,Nakao, Akira,Stealey, Michael A.,Villamil, Clara I.,et al.
-
p. 1052 - 1061
(2007/10/02)
-