Iron-Catalyzed Highly para-Selective Difluoromethylation of Arenes

Abstract

Direct functionalization of a C−H bond at either the meta or para position by only changing the catalyst system poses a significant challenge. We herein report the [Fe(TPP)Cl]-enabled, selective, C−H difluoromethylation of arenes using BrCF 2 CO 2 Et as the difluoromethylation source, which successfully altered the selectivity from the meta to the para position. A preliminary mechanistic study revealed the iron porphyrin complex not only activated the aromatic ring but also induced para selectivity due to the influence of ligand sterics.

Organozinc Pivalates for Cobalt-Catalyzed Difluoroalkylarylation of Alkenes and Mechanistic Insights

“…These ndings are consistent with the in situ generated low-valent cobalt(I)species might be the active catalyst for the current three-component cross-coupling reaction. A series of EPR spin-trapping experiments show the existence of C-centered radicals trapped by DMPO (g=2.0066, A N = 13.9 G, A H = 19.3 G), which was considered to be •CF 2 R. [86] These results strongly supported the single electron transfer progress for the activation of BrCF 2 R was only promoted by the in situ formed Co(I)species (Scheme 9e).…”

Mimicking Enzymes: Taking Advantage of the Substrate-Recognition Properties of Metalloporphyrins in Supramolecular Catalysis

“…Since synthetic methodologies enabling access to highly elaborated metalloporphyrins in a straightforward manner are available nowadays, novel progress exploiting the substrate-recognition properties of metalloporphyrins is anticipated. 93 Overall, this review showcases that there is much knowledge to be explored beyond the more classical reactivity associated with the metal embedded in a porphyrin core. [94][95][96][97][98][99][100]…”

Recent advances in transition-metal catalyzed directed C–H functionalization with fluorinated building blocks

“…The para -selective difluoroacetylation of various ketones, aldehydes, esters and heteroarenes has also been developed via a transient regulating strategy, which does not involve any C-H activation step. The transition metals employed were Pd, 193 Ru 194 and Fe 195 for such para -selectivity. The ligands used in the reaction play an important role and the pathway involves the single electron transfer process.…”