Oxidative mono- and di- vinylation of 1-phenylpyrazole: Aqueous Rh(III)-catalyzed cross dehydrogenative coupling reactions

A jackpot C–H activation protocol using simple ruthenium catalyst in deep eutectic solvents

“…In some cases, the corresponding double addition product to 1-phenylpyrazole was observed (compounds 18a and 18b ), when different alkyl acrylate derivatives were employed along with small amounts of the monoalkenylated derivative. Even though it is well stablished that this transformation undergoes directed double alkenylation under Pd or Rh catalysts at high temperatures, 49,50 the use of Ru catalyst has been proved to provide a mixture of both the mono and the double alkenylated product. 51 To obtain the monoalkenylated product, a single equivalent of 4 was used.…”

Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)–H bonds

“…Joshi, Smith and co-workers developed a Rh-catalysed CDC protocol for vinylation of 1-phenylpyrazoles in water medium (Scheme 16). 30 A Rh( iii )- N , O -salicylaldimine organometallic complex with a half-sandwich structure was employed as the ligand precursor. The catalyst loading can be lowered to 0.5 mol%.…”

Selenium-Directed Ortho C–H Activation of Benzyl Selenide by a Selenated NHC–Half-Pincer Ruthenium(II) Complex

“…A plausible mechanism has been proposed purely based on available literature evidences (Scheme ). , The catalytic process started with the displacement of Cl from complex ( 1 ) by Cu­(OAc) 2 , resulting in an active catalytic species (a). With the involvement of the OAc ligand, thioether is chelated and undergoes ortho -metalation deprotonation at the benzyl ring, culminating in a five-member ruthenacycle (c).…”

“…In this regard, usage of the directing groups has been demonstrated to be an effective way of increasing reactivity and regulating selectivity in a C–H functionalization reaction. The covalently appended directing group served as an ancillary ligand to assure proximal ortho, , meta, − and para , C–H functionalization in the course of the most recent two decades. Currently, many directing groups have been used, including ester, ethers, imines, amide, ketones, carbamates, aldehyde, carboxylic acid, phosphine, and hydrosilanes .…”