Search

The C–S cross‐coupling reaction is a very efficient and powerful tool for constructing C–S bonds. Despite the well‐reported C–S cross‐coupling protocols using aryl halides, this reaction using sp2‐hybridized nonaromatic halides is still challenging. Herein, we report light‐assisted C–S cross‐coupling between thiols and 5‐chlorobenzofurazan under blue LED irradiation. We used a new nickel catalyst to synthesize 11 unpublished compounds. Furthermore, we assessed the mechanism and the influence of light irradiation on this reaction and proposed a plausible mechanism that is mediated by the excited state of the nickel catalyst promoted by irradiation with blue light and the C–S coupling product formed. Notably, C–S cross‐coupling under light irradiation was performed for the first time using a nickel catalyst in the absence of an external photocatalyst. We demonstrated that because nickel has a low energy barrier for oxidative addition, this protocol proceeded efficiently using chlorine as a leaving group, and the excited state of the nickel catalyst promoted reductive elimination with a lower energy barrier. It is important to mention that the procedure was tolerated by many functional groups within the thiol, affording a greater than 99% yield after reacting for 6 h. [ABSTRACT FROM AUTHOR]

An efficient and unprecedented S-glycosylation reaction of benzo-2,1,3-thiadiazole at the C-5-position using a Pd-G3 Xantphos palladacycle precatalyst has been described. This methodology showed a high functional group tolerance to the electrophilic partner and can be successfully applied to a variety of β-mono- and di-thiosugar derivatives. A series of thioglycoside derivatives from benzo-2,1,3-thiadiazole were prepared in good to excellent yields under mild and operationally simple reaction conditions. [ABSTRACT FROM AUTHOR]

A new and effective palladium catalyst supported on a magnesium organosilicate for application in the Heck reaction is presented. A group of compounds comprising 22 examples were synthesized in moderate to high yields (up to 99%) within a short time. The palladium supported on magnesium organosilicate catalyst was characterized as an amorphous solid by SEM, containing around 33% of palladium inside the solid, and even with this low quantity of palladium, the catalyst was very efficient in the Heck reaction. Besides, based on the Scherrer equation, the crystallite size of the synthesized palladium nanoparticles was ultrasmall (around 1.3 nm). This strategy is a simple and efficient route for the formation of C–C bonds via the Heck cross-coupling reaction. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed Suzuki–Miyaura cross-coupling reaction is one of the most important and efficient reactions to prepare a variety of organic compounds, including biaryls. Despite the overwhelming number of reports related to this topic, some methodological difficulties persist in terms of catalyst handling, recovery, and reuse, as well as the reaction media. This work reports the rational design of new, efficient, cost-effective, and reusable palladium catalysts supported on synthetic talc for the Suzuki–Miyaura reaction. From the results, key points were identified: both designed catalysts accelerated the reaction in EtOH and an open-flask setup, affording moderate to excellent yields within a short time (e.g., 30 min) even for deactivated aryl halides; the protocol can be applied to a great number of both cross-coupling partners, showing an excellent functional group tolerance; the catalysts can be recovered and reused without significant loss of activity. This protocol was used for the synthesis of a precursor of angiotensin II inhibitors such as valsartan, losartan, irbesartan, and telmisartan. [ABSTRACT FROM AUTHOR]

Abstract: A simple, efficient and green methodology for the C−S cross‐coupling reaction using Pd(L‐Pro)2 as a heterogeneous catalyst was developed involving aryl iodides, thiols, green‐solvent and a low catalytic loading of palladium prolinate. In addition, the catalyst turned out to be recyclable and the products were obtained in good to excellent yields. [ABSTRACT FROM AUTHOR]

An abstract of the article regarding the insertion of a new catalyst in thia-Michael reactions known as the bis-L-zinc prolinate by Mariana Pompilio Darbem, Andrelson Wellington Rinaldi and Nelson Luís C. Domingues is presented.

Hybrid materials have seized attention from scientific community mainly as heterogenic catalysts in organic reactions on a large scale succeeding in some organic compounds with high yields. One of the most important classes of hybrid materials used for this purpose involves the complexation of Zn and aminoacids. Herein, we introduced Zn[Pro]2 and Zn[Gly]2 in the synthesis of several β-enaminones via solvent free protocol and using an ultrasound device. [ABSTRACT FROM AUTHOR]