- Carbon dots as photocatalysts for organic synthesis: Metal-free methylene-oxygen-bond photocleavage
-
We report for the first time that irradiation of four different citric acid-derived carbon dots (CDs), in the absence of any other redox mediators, promotes an organic reaction. In this proof-of-concept study methylene-oxygen bond reductive photocleavage in N-methyl-4-picolinium esters is demonstrated. Cyclic voltammetry and UV-Vis spectra of the CDs and of the esters indicate that photocleavage reactivity correlates with the redox properties and the relative energies expressed in the Fermi scale. A photo-fragmentation mechanism is proposed. This study offers a new possibility to employ inexpensive and readily available CDs to promote photo-organic reactions.
- Cailotto, Simone,Negrato, Matteo,Daniele, Salvatore,Luque, Rafael,Selva, Maurizio,Amadio, Emanuele,Perosa, Alvise
-
supporting information
p. 1145 - 1149
(2020/03/11)
-
- Construction of 1,2,4-Triazole Derivatives via Cyclocondensation of Alkylidene Dihydropyridines and Aryldiazonium Salts
-
Alkylidene dihydropyridines (anhydrobases) prepared via dearomatization of N-acylated 4-(aminomethyl)pyridines participate in [3 + 2] cyclocondensation reactions with aryldiazonium cations to afford substituted 1,2,4-triazolium salts or neutral 1,2,4-tria
- Joshi, Madhur S.,Pigge, F.Christopher
-
supporting information
p. 5916 - 5919
(2016/11/29)
-
- Base-catalyzed retro-Claisen condensation: A convenient esterification of alcohols via C-C bond cleavage of ketones to afford acylating sources
-
The base-catalyzed esterification of alcohols via retro-Claisen condensation has been demonstrated for the first time. A variety of alcohols including aryl- and heteroaryl methanols as well as aliphatic ones underwent efficient acylation to give the ester products in reasonable to good yields upon isolation. Not only conventional 1,3-diketones but also strong electron-withdrawing group containing acetophenones could serve as the acylating suppliers. The synthetic protocol is operationally simple and adaptable to a broad substrate scope. It complements the existed esterification via the retro-Claisen condensation, and enlarges this benign synthetic methodology.
- Xie, Feng,Yan, Fengxia,Chen, Mengmeng,Zhang, Min
-
p. 29502 - 29508
(2014/08/05)
-
- Hydroxymethylations of aryl halides by Pd-catalyzed cross-couplings with (benzoyloxy)methylzinc iodide - Scope and limitations of the reaction
-
Palladium-catalyzed cross-coupling reactions of (benzoyloxymethyl)zinc iodide with diverse (het)aryl halides leading to (benzoyloxymethyl)(het)arenes were studied to define the scope of this reaction. It has been found that this reaction is only applicable for electron-deficient aryl halides and the most efficient it is for 2-halopyridines and 4-halopyrimidines. Deprotection of the intermediates gives (hydroxymethyl)pyridines and -pyrimidines in high yields. Georg Thieme Verlag Stuttgart.
- Hasník, Zbyněk,?ilhár, Peter,Hocek, Michal
-
p. 543 - 546
(2008/12/22)
-
- C-O bond fragmentation of 4-picolyl- and N-methyl-4-picolinium esters triggered by photochemical electron transfer
-
Photochemical reduction of several 4-picolyl- and N-methyl-4-picolinium esters was examined using product analysis, laser flash photolysis, and fluorescence quenching. It is demonstrated that the radical (anions) formed in these reactions readily fragment to yield a carboxylic acid and a 4-pyridylmethyl radical intermediate. The high chemical and quantum yields observed for these photoreactions suggests that these esters can be used as photolabile protecting groups.
- Sundararajan, Chitra,Falvey, Daniel E.
-
p. 5547 - 5554
(2007/10/03)
-
- Chemically-tagged Mitsunobu reagents for use in solution-phase chemical library synthesis
-
A general method for high-throughput product purification of Mitsunobu reactions is described. Tagged phosphine and azodicarboxylate reagents are used to synthesize individual library members in solution-phase. Workup and purification are easily accomplished by post-reaction sequestration of the tagged reagents and reagent byproducts by a complementary functionalized ion exchange resin. The reagents are utilized in a 3 step library synthesis.
- Starkey, Gale W.,Parlow, John J.,Flynn, Daniel L.
-
p. 2385 - 2390
(2007/10/03)
-
- DECOMPOSITION DU PEROXYDE DE BENZOYLE DANS LES MELANGES BENZENE/X-4 PYRIDINES (X=CH3, H, CN). ETUDE CINETIQUE ET INFLUENCE DES SUBSTITUANTS SUR LA REACTIVITE NUCLEOPHILE ET RADICALAIRE DE L'ATOME D'AZOTE
-
Effect of a 4-substituent in the pyridine ring upon the decomposition kinetics of benzoyl peroxide in 4-X pyridine/benzene binary mixtures (X=CH3,H,CN) has been studied.The second-order rate constant for the pyridine-induced decomposition was 2x10-6 lmol-1s-1 and in 4-methylpyridine it was 10-5 lmol-1s-1, a five-fold increase, whereas there was no nucleophilic attack on the peroxide oxygen atoms of benzoyl peroxide by 4-cyanopyridine.The surprisingly high increase of the radical-induced decomposition in 4-cyanopyridine might result from the attack at the nitrogen atom of the pyridine ring by the phenyl radical, the 1-phenylpyridinyl radical being stabilized by the cyano group.
- Vidal, S.,Court, J.,Bonnier, J.M.
-
p. 4911 - 4920
(2007/10/02)
-