Boron‐Catalyzed Dehydrative Friedel‐Crafts Alkylation of Arenes Using β ‐Hydroxyl Ketone as MVK Precursor

H2 O ⋅ B(C6 F5 )3 -Catalyzed para-Alkylation of Anilines with Alkenes Applied to Late-Stage Functionalization of Non-Steroidal Anti-Inflammatory Drugs

Anilines are core motifs in a variety of important molecules including medicines, materials and agrochemicals. We report a straightforward procedure that allows access to new chemical space of anilines via their para-C-H alkylation. The method utilizes commercially available catalytic H2 O ⋅ B(C6 F5 )3 and is highly selective for para-C-alkylation (over N-alkylation and ortho-C-alkylation) of anilines, with a wide scope in both the aniline substrates and alkene coupling partners. Readily available alkenes are used, and include new classes of alkene for the first time. The mild reaction conditions have allowed the procedure to be applied to the late-stage-functionalization of non-steroidal anti-inflammatory drugs (NSAIDs), including fenamic acids and diclofenac. The formed novel NSAID derivatives display improved anti-inflammatory properties over the parent NSAID structure.

Oxidative cross-coupling of quinoxalinones with indoles enabled by acidochromism

An oxidative cross-coupling of quinoxalinones with indole derivatives via B(C₆F₅)₃·H₂O induced acidochromism of quinoxalinone derivatives was developed under mild and external photocatalyst-free conditions. The reaction shows excellent substrate scope, accommodating a wide range of functional groups. The usefulness of this strategy was demonstrated by the synthesis of the natural products Azacephalandole A and Cephalandole A in high yields. Moreover, the products are fluorophores showing prevalent fluorescence properties with a wide emission range and good relative quantum yields.

Boron Lewis Acid Catalysis Enables the Direct Cyanation of Benzyl Alcohols by Means of Isonitrile as Cyanide Source

The development of an efficient and straightforward method for cyanation of alcohols is of great value. However, the cyanation of alcohols always requires toxic cyanide sources. Herein, an unprecedented synthetic application of an isonitrile as a safer cyanide source in B(C₆F₅)₃-catalyzed direct cyanation of alcohols is reported. With this approach, a wide range of valuable α-aryl nitriles was synthesized in good to excellent yields (up to 98%). The reaction can be scaled up and the practicability of this approach is further manifested in the synthesis of an anti-inflammatory drug, naproxen. Moreover, experimental studies were performed to illustrate the reaction mechanism.

The B(C6F5)3·H2O promoted synthesis of fluoroalkylated 3,3',3''-trisindolylmethanes from fluorocarboxylic acids and indoles

Trisindolylmethanes (TIMs) exist in many bioactive natural products and are frequently applied in medicinal chemistry and materials science. Herein, a simple and efficient protocol promoted by B(C₆F₅)₃·H₂O for the synthesis of their fluoroalkylated analogues, fluoroalkylated 3,3',3''-TIMs, is reported for the first time. Easily accessible fluorocarboxylic acids are utilized as the fluoroalkyl sources, exhibiting an obvious fluorine effect. This convenient and green process features mild and metal-free conditions, easy scale-up, and an environmentally friendly byproduct.

Arylboronic Acid Catalyzed Dehydrative Mono-/Dialkylation Reactions of β-Ketoacids and Alcohols

The dehydrative mono-/dialkylation reactions of alcohols and β-ketoacids were realized under arylboronic acid catalysis, furnishing a series of β-aryl ketones and β-ketoesters in yields of 15-99%, with CO₂ and H₂O being the byproducts. In this context, the decarboxylative alkylation reaction occurred to give β-aryl ketones at 50 °C, while the decarboxylation was suppressed to generate dialkylated ester products at 0 °C. A possible catalytic cycle was proposed based on control experiments.

Borane-Catalyzed Dehydrogenative C‒C Bond Formation of Indoles with N-Tosylhydrazones: An Experimental and Computational Study

A novel dehydrogenative C‒C bond formation of indoles and N-tosylhydrazones to di(indolyl)methanes (DIMs) has been demonstrated using tris(pentafluorophenyl)borane as catalyst. A wide range of functional groups can be tolerated under...

B(C6F5)3-Catalyzed Electron Donor-Acceptor Complex-Mediated Aerobic Sulfenylation of Indoles under Visible-Light Conditions

An efficient B(C₆F₅)₃-catalyzed aerobic oxidative C-S cross-coupling reaction of thiophenol with indoles was developed, affording a wide range of diaryl sulfides in good yields. An electron donor-acceptor complex between B(C₆F₅)₃ and indoles was formed, facilitating the photoinduced single-electron transfer (SET) from indole substrates to the B(C₆F₅)₃ catalyst. This protocol demonstrates a new reaction model using B(C₆F₅)₃ as a single-electron oxidant.