Efficient methylation of anilines with methanol catalysed by cyclometalated ruthenium complexes

Cyclometalated ruthenium complexes4-10allow the effective methylation of anilines with methanol to selectively giveN-methylanilines. This hydrogen autotransfer procedure proceeds under mild conditions (60 °C) in a practical manner (NaOH as base). Mechanistic investigations suggest an active homogenous ruthenium complex and β-hydride elimination of methanol as the rate determining step. © The Royal Society of Chemistry 2021

A Zinc-Mediated Deprotective Annulation Approach to New Polycyclic Heterocycles

A straightforward approach to new polycyclic heterocycles, 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones, is presented. It is based on the ZnCl2-promoted deprotective 6-endo-dig heterocyclization of N-Boc-2-alkynylbenzimidazoles under mild conditions (CH2Cl2, 40 °C for 3 h). The zinc center plays a dual role, as it promotes Boc deprotection (with formation of the tert-butyl carbocation, which can be trapped by substrates bearing a nucleophilic group) and activates the triple bond toward intramolecular nucleophilic attack by the carbamate group. The structure of representative products has been confirmed by X-ray diffraction analysis

Advances in Palladium-Catalyzed Carboxylation Reactions

In this short review, we highlight the advancements in the field of palladium-catalyzed carbon dioxide utilization for the synthesis of high value added organic molecules. The review is structured on the basis of the kind of substrate undergoing the Pd-catalyzed carboxylation process. Accordingly, after the introductory section, the main sections of the review will illustrate Pd-catalyzed carboxylation of olefinic substrates, acetylenic substrates, and other substrates (aryl halides and triflates)

Palladium-Catalyzed Cyclocarbonylation Approach to Thiadiazafluorenones. A Correction

The palladium-catalyzed carbonylation of 2-(propynylthio)benzimidazoles bearing a terminal triple bond leads to 2-methyl-1-thia-4a,9-diazafluoren-4-ones, instead of the previously reported 3-methyl isomers. This has been unequivocally established by XRD analysis of a representative product, that is, 2-methyl-1-thia-4a,9-diazafluoren-4-one. A correction is therefore provided here in order to rectify the previous erroneous assignment of the position of the methyl group in the final products. Moreover, the process has been generalized to the use of substrates bearing an internal triple bond, which led to 3-alkyl-2-methyl-1-thia-4a,9-diazafluoren-4-ones, whose structure was confirmed by XRD analysis of two representative derivatives. An unexpected structural rearrangement must take place to account for product formation with both kind of substrates. This probably corresponds to a palladium-promoted propargyl-allene rearrangement, with elimination a thiolate and an allenylpalladium intermediate, which is then followed by nucleophilic attack of the thiolate to the central carbon of allene moiety and cyclocarbonylation

Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α‐Alkylation of Ketones with Alcohols

Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H− as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α-Alkylation of Ketones with Alcohols

Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H− as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Synthesis of 1,3-oxazine-2,4-diones by DBU-catalyzed incorporation of carbon dioxide into 3-ynamides

A new process for the utilization of carbon dioxide to give high value added 1,3-oxazine-2,4-diones is presented. It is based on the catalytic carboxylative heterocyclization of readily available 3-ynamides, using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as organocatalyst. The reaction, which takes place under relatively mild conditions [80 °C for 15 h in a 3:1 mixture (v/v) of MeCN-HC(OMe)3, under 30 atm of CO2] proceeds through an ordered sequence of steps, involving substrate deprotonation by DBU, nucleophilic attack to CO2, 6-exo-dig cyclization, and isomerization, to give the final products in 44–85 % yields over 16 example

Synthesis and Photochemical Characterization of Indolizine Fluorophores Obtained by a Multicomponent Palladium Iodide‒Catalyzed Oxidative Aminocarbonylation Approach

A catalytic carbonylative method for the direct, multicomponent synthesis of indolizine fluorophores has been developed. The process is based on the PdI2/KI‐catalyzed oxidative aminocarbonylation of 2‐(pyridin‐2‐yl)pent‐4‐yn‐1‐carbonyl compounds leading to the corresponding 2‐ynamide intermediates, followed in situ by 5‐exo‐dig cyclization (by amine‐promoted conjugate addition of the pyridine ring nitrogen) and aromatization, to give the finally isolated N,N‐disubstituted 2‐(indolizin‐3‐yl)acetamides. Reactions are carried out under relatively mild conditions (100 °C under 20 atm of a 4:1 mixture CO‒air for 6‐15 h) in MeCN as the solvent and with a low catalyst loading (0.33 mol% PdI2), in the presence of 0.5 equiv of KI and 3 equiv of a secondary amine. The optical properties of representative 2‐(indolizin‐3‐yl)acetamide products have also been investigate

Synthesis, computational evaluation and pharmacological assessment of acetylsalicylic esters as anti-inflammatory agents

A convenient approach to the synthesis of alkyl esters of aspirin (ASA-OR) has been developed. The synthesis of ASA-OR has been realized in two steps: (1) direct esterification of salicylic acid with alcohols in the presence of dicyclohexylcarbodiimide to give alkyl salicylates (SAL-OR); (2) acetylation of SAL-OR with acetyl chloride to yield ASA-OR. Molecular mechanics simulations, performed to calculate the kinetic radii of several ASA-OR, indicated that the pentyl and hexyl acetylsalicylates possess the best properties to cross cell membranes. The in vitro biological tests demonstrate their anti-inflammatory activity, superimposable to that of aspirin. The results of our study suggest that ASA-OR may be used as anti-inflammatory drugs for topical application

Supporting Information for the article "Synthesis and Antibacterial Activity of Polymerizable Acryloyloxyalkyltriethyl Ammonium Salts", published in ChemPlusChem 2017, 82(10), 1235-1244.

<p>Supporting Information for the article "Synthesis and Antibacterial Activity of Polymerizable Acryloyloxyalkyltriethyl Ammonium Salts", published in ChemPlusChem 2017, 82(10), 1235-1244 (DOI: 10.1002/cplu.201700194).</p> <p>The file is available free of charge at the publisher's website at the following URL: http://onlinelibrary.wiley.com/store/10.1002/cplu.201700194/asset/supinfo/cplu201700194-sup-0001-misc_information.pdf?v=1&s=3935a62996b49f0a39ddac08c0d37928db2dc817</p> <p>The file contains the characterization data and the copy of 1H and 13C NMR Spectra for all product synthesized in the paper published in ChemPlusChem 2017, 82(10), 1235-1244 (DOI: 10.1002/cplu.201700194).</p> <p> </p