In this Review, we summarize the current state of the art in late‐transition‐metal‐catalyzed reactions of acyl fluorides, covering both their synthesis and further transformations. In organic reactions, the relationship between stability and reactivity of the starting substrates is usually characterized by a trade‐off. Yet, acyl fluorides display a very good balance between these properties, which is mostly due to their moderate electrophilicity. Thus, acyl fluorides (RCOF) can be used as versatile building blocks in transition‐metal‐catalyzed reactions, for example, as an “RCO” source in acyl coupling reactions, as an “R” source in decarbonylative coupling reactions, and as an “F” source in fluorination reactions. Starting from the cleavage of the acyl C−F bond in acyl fluorides, various transformations are accessible, including C−C, C−H, C−B, and C−F bond‐forming reactions that are catalyzed by transition‐metal catalysts that contain the Group 9–11 metals Co, Rh, Ir, Ni, Pd, or Cu.
Described herein is that the catalytic construction of N-substituted five- and six-membered lactams from keto acids with primary amines by reductive amination, using an indium/silane combination. This relatively benign and safe catalyst/reductant system tolerates the use of a variety of functional groups, especially ones that are reduction-sensitive. A direct switch from synthesizing lactams to synthesizing cyclic amines is achieved by changing the catalyst from In(OAc)3 to InI3. This conversion occurs by further reduction of the lactam using the indium/silane pair.
Ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides were developed using a Pd(OAc)/EtSiH combination. When tricyclohexylphosphine (PCy) was used as the ligand, aldehydes were obtained as simple reductive conversion products. The use of 1,2-bis(dicyclohexylphosphino)ethane (CyP(CH)PCy, DCPE) as the ligand, however, favored the formation of hydrocarbons, which are decarbonylative reduction products.
The combination of a catalytic amount of InCl3 and acetic anhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation of a geminal diacetate intermediate, which was generated in situ from an aldehyde and an acid anhydride with the assistance of an indium catalyst.
The first palladium‐catalyzed construction of ketones through Suzuki–Miyaura reaction by using acid fluorides is described. In contrast to typical acyl electrophiles such as acid chlorides, acid fluorides are uncommon acyl electrophiles to use in boron‐based coupling reactions, probably due to a high level of stability toward nucleophiles. This first attempt to use acid fluorides as a coupling partner with boronic acids allowed highly functional group tolerance and a wide substrate scope while affording various ketones in effective yields.
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