Kumada Coupling of Aryl and Vinyl Tosylates under Mild Conditions

Abstract

[Reaction: see text]. Aryl and alkenyl tosylates are easily prepared, inexpensive and, thus, attractive for transition-metal-catalyzed couplings, but their reactivity is low. We report examples of mild, palladium-catalyzed coupling of aryl, alkenyl, and alkyl Grignard reagents with aryl and alkenyl tosylates. The resulting biaryls, vinylarenes, and alkylarenes were isolated in good to excellent yield. These couplings were conducted with a nearly equimolar ratio of the two reactants, and many examples were conducted at room temperature.

Well‐Defined Air‐Stable Palladium HASPO Complexes for Efficient Kumada–Corriu Cross‐Couplings of (Hetero)Aryl or Alkenyl Tosylates

“…Specifically, generally applicable palladium-catalyzed crosscoupling reactions between organomagnesium reagents and unactivated aryl tosylates were elegantly accomplished with a palladium complex derived from an electron-rich analogue of the Josiphos ligand. [7][8][9] Unfortunately, heterocyclic [10] tosylates bearing Lewis-basic nitrogen-containing functionalities proved to be detrimental to the catalytic activity of the Josiphos-based palladium complex. [7,8] We, on the contrary, devised an in situ generated catalyst of air-stable heteroatom-substituted [11] secondary phosphine oxide (HASPO) [12] preligands for challenging arylations of inter alia aryl bromides, chlorides, and fluorides, [13] which notably proved to be amenable to Kumada-Corriu coupling reactions of unactivated aryl tosylates as well.…”

STIR: Redox-Switchable Olefin Polymerization Catalysis: Electronically Tunable Ligands for Controlled Polymer Synthesis

“…Ferrocenyl derived ligands are well known and have applications ranging from materials 7 to ligands for transition metal catalyzed carbon-carbon and carbon-heteroatom bond forming reactions. 8,9 Their derivitization has been extensively studied, and perhaps most importantly, ferrocene's redox behavior is well understood as its Fe II /Fe III transition is easily obtainable electrochemically or through the use of many well-known chemical oxidants or reductants. 10 Though ferrocene is an ideal target, our studies of Ni-and Pd-based catalysts hint that simpler ligands may also be appropriate to achieve redox-switching, which will be described in later sections of this report.…”

Pd‐Catalyzed CN Bond Formation with Heteroaromatic Tosylates

“…While acyclic secondary amides failed to couple with the heteroaromatic tosylates in satisfactory yields under the applied conditions, lactams demonstrated to be good nucleophiles for the amidations (entries [13][14][15][16]. [7] Five-and sevenmembered lactams provided good yields of the amidation products and, gratifyingly, even a b-lactam could be exploited effectively for C À N bond formation with a pyrimidyl tosylate (entry 16).…”

“…On the other hand, switching to the JosiPhos type ligand PPF-PtBu, [6] 45 could be secured in an acceptable 46 % isolated yield (Scheme 4). [13] www.chemeurj.org…”