Chemoselective Activation of sp³ vs sp² C–H Bonds with Pd(II)

Abstract

The first selective coupling of a carbon nucleophile with methyl, ethyl, propyl, and butyl arenes in the absence of a directing group is described. Pd(OAc)2 double C–H activation displays remarkable selectivity for the terminal methyl sites in alkyl arenes, rather than the more commonly observed arene sp2 C–H activation. Mechanistic studies indicate the intermediacy of an azlactone dimer, obtained from oxidation with Pd(OAc)2, and are consistent with a Pd-catalyzed C–H activation vs a radical process. The observed reactivity establishes that typical reaction solvents (e.g., toluene) can readily participate in C–H activation chemistry.

Acid‐Sensitive BODIPY Dyes: Synthesis through Pd‐Catalyzed Direct C(sp3)−H Arylation and Photophysics

“…[16] Afterwards, the Ortiz group reported as imilar reaction. [18] Inspired by this, we speculated that there could be ap ossibility to realize direct C(sp 3 )ÀHa rylation between unactivated BODIPYs( methyl at 8-position) and halogenated arenes through this established deprotonative cross-coupling process (Scheme 1). We noticedt hat the established deprotonative cross-couplingp rocess (DCCP) for directC (sp 3 )ÀHa rylation requiresa na cidic CÀHb ond.…”

Katalyse mit durch sichtbares Licht angeregten Palladiumkomplexen

“…[2] Unlängst wurde berichtet, dass die Anregung mittels sichtbaren Lichts in Abwesenheit exogener Photosensibilisatoren [3][4][5] dazu führt, dass gebildete,p hotoangeregte Pd-Komplexe Einelektronentransfer-Prozesse (SETs;s ingleelectron transfers) durchlaufen, die zur Bildung hybrider Pd/ Radikal-Spezies [6] über einen Pd 0 /Pd I -Reaktionspfad führen (Schema 1, angeregter Zustand). [2] Unlängst wurde berichtet, dass die Anregung mittels sichtbaren Lichts in Abwesenheit exogener Photosensibilisatoren [3][4][5] dazu führt, dass gebildete,p hotoangeregte Pd-Komplexe Einelektronentransfer-Prozesse (SETs;s ingleelectron transfers) durchlaufen, die zur Bildung hybrider Pd/ Radikal-Spezies [6] über einen Pd 0 /Pd I -Reaktionspfad führen (Schema 1, angeregter Zustand).…”

Pd(II)-catalyzed Chelation-assisted Cross Dehydrogenative Coupling between Unactivated C(sp3)–H Bonds in Aliphatic Amides and Benzylic C–H Bonds in Toluene Derivatives

“…3c, 8 To the best of our knowledge, no examples of the intermolecular CDC of unactivated C(sp 3 )H bonds, in which chelation-assistance if involved, have been reported. 9 We wish to report here on the first example of such a CDC of C(sp 3 )H bonds by taking advantage of N,N-bidentate chelation assistance.…”