59880-88-5Relevant articles and documents
N-Heterocyclic Carbene Catalyzed Photoenolization/Diels–Alder Reaction of Acid Fluorides
Agrawal, Arush,G?tze, Jan P.,Golz, Paul,Hopkinson, Matthew N.,Mavroskoufis, Andreas,Rajes, Keerthana,Ru?, Vincent
supporting information, p. 3190 - 3194 (2020/01/24)
The combination of light activation and N-heterocyclic carbene (NHC) organocatalysis has enabled the use of acid fluorides as substrates in a UVA-light-mediated photochemical transformation previously observed only with aromatic aldehydes and ketones. Stoichiometric studies and TD-DFT calculations support a mechanism involving the photoactivation of an ortho-toluoyl azolium intermediate, which exhibits “ketone-like” photochemical reactivity under UVA irradiation. Using this photo-NHC catalysis approach, a novel photoenolization/Diels–Alder (PEDA) process was developed that leads to diverse isochroman-1-one derivatives.
Base-free nickel-catalysed decarbonylative Suzuki–Miyaura coupling of acid fluorides
Malapit, Christian A.,Bour, James R.,Brigham, Conor E.,Sanford, Melanie S.
, p. 100 - 104 (2018/11/25)
The Suzuki–Miyaura cross-coupling of organoboron nucleophiles with aryl halide electrophiles is one of the most widely used carbon–carbon bond-forming reactions in organic and medicinal chemistry1,2. A key challenge associated with these transformations is that they generally require the addition of an exogenous base, the role of which is to enable transmetallation between the organoboron nucleophile and the metal catalyst3. This requirement limits the substrate scope of the reaction because the added base promotes competitive decomposition of many organoboron substrates3–5. As such, considerable research has focused on strategies for mitigating base-mediated side reactions6–12. Previous efforts have primarily focused either on designing strategically masked organoboron reagents (to slow base-mediated decomposition)6–8 or on developing highly active palladium precatalysts (to accelerate cross-coupling relative to base-mediated decomposition pathways)10–12. An attractive alternative approach involves identifying combinations of catalyst and electrophile that enable Suzuki–Miyaura-type reactions to proceed without an exogenous base12–14. Here we use this approach to develop a nickel-catalysed coupling of aryl boronic acids with acid fluorides15–17, which are formed in situ from readily available carboxylic acids18–22. This combination of catalyst and electrophile enables a mechanistic manifold in which a ‘transmetallation-active’ aryl nickel fluoride intermediate is generated directly in the catalytic cycle13,16. As such, this transformation does not require an exogenous base and is applicable to a wide range of base-sensitive boronic acids and biologically active carboxylic acids.
