Copper-catalyzed chemoselective cross-coupling reaction of thioamides and α-diazocarbonyl compounds: Synthesis of enaminones

Blue LED-Mediated Synthesis of 3-Arylidene Oxindoles

Blue LED-promoted cross-coupling olefination of symmetrical and unsymmetrical 3-arylidene oxindoles has been described from diazoindolones and diphenylmethanethiones. Thermal olefin isomerization and stereoselective synthesis of 3-arylidene oxindoles were also demonstrated in good yield.

Coupling of acceptor-substituted diazo compounds and tertiary thioamides: synthesis of enamino carbonyl compounds and their pharmacological evaluation

This paper describes the synthesis of enamino carbonyl compounds by the copper(i)-catalyzed coupling of acceptor-substituted diazo compounds and tertiary thioamides. We plan to use this method to synthesize indolizidine (−)-237D analogs to find α6-selective antismoking agents. Therefore, we also performed in silico α6-nAchRs binding studies of selected products. Compounds with low root-mean-square deviation values showed more favorable binding free energies. We also report preliminary pharmacokinetic data on indolizidine (−)-237D and found it to have weak activity at CYP3A4. In addition, as enamino carbonyl compounds are also known for antimicrobial properties, we screened previously reported and new enamino carbonyl compounds for antibacterial, antimicrobial, and antifungal properties. Eleven compounds showed significant antimicrobial activities.

This paper describes the synthesis of enamino carbonyl compounds by the copper(i)-catalyzed coupling of acceptor-substituted diazo compounds and tertiary thioamides.

Pd-Catalyzed Coupling of Thioamides with N-Tosylhydrazones/Trapping by Esters Cascade Reaction

N,N-Disubstituted thioamides coupled with N-tosylhydrazones under Pd(TFA)₂/^tBuXPhos catalyst and NaO^tBu, and the intermediates from palladium carbene migratory insertion containing β-hydrogen were trapped by intramolecular esters activated by BF₃·Et₂O instead of undergoing β-H elimination, providing polyfunctional thiophen-3(2H)-ones with sulfur-containing tetrasubstituted carbon centers in moderate to good yields. The reaction features the formation of three bonds in a single operation, odorless, safe, and easily available substrates, wide substrate scope, and excellent functional group tolerance.

Application of NMR Spectroscopy for the Detection of Equilibrating E-Z Diastereomers

Conjugation can lower the energy barrier for unsaturated C-C bond rotations, resulting in a mixture of equilibrating diastereomers at room temperature. Therefore, methods claiming diastereoselective synthesis of conjugated double bonds often require proof that the observed diastereomeric ratio is not because of the diastereomeric equilibration of the product. Variable-temperature (VT) NMR experiments are commonly used to distinguish between the two possibilities. However, the VT technique requires accessories for the NMR spectrometer and more setup time. Here, we show that the rarely used application of 1-D and 2-D nuclear Overhauser effect spectroscopy experiments for the detection of the equilibrating diastereomers is a convenient alternative to the VT technique.

Copper-Catalyzed Coupling of Thioamides and Donor/Acceptor-Substituted Carbenoids: Synthesis of Enamino Esters and Enaminones

The coupling of thioamides and donor/acceptor-substituted diazocarbonyl compounds is reported for the first time. The present report provides a mild, catalytic method that couples thioamides and donor/acceptor-substituted diazocarbonyl compounds to form enamino esters and enaminones. Unlike traditional methods for the synthesis of enamino esters and enaminones from thioamides, both N-alkyl thioamides and thiocarbamates are suitable substrates in this coupling reaction. Copper(I) bromide catalyzes the reaction and provides enamino esters and enaminones chemo- and diastereoselectively in less time than Rh₂(OAc)₄ or Ru(PPh₃)₃Cl₂ catalysts.

Carbon-Carbon Bond Formation by Reaction of Rhodium Azavinylcarbenes with Secondary Amides: Access to Indigo Analogues from Isatins

A novel protocol for the synthesis of unsymmetrical indigo-like (E)-α-amino enaminones by rhodium-catalyzed transformations of isatins with 1-tosyl-1,2,3-triazoles has been developed. A plausible reaction mechanism is proposed to account for the formation of structurally important unsymmetrical indigo analogues, which represents a new strategy for C-C bond formation based on the transformations of secondary amides and rhodium azavinylcarbenes.