Fluoride-Catalyzed Cross-Coupling of Carbamoyl Fluorides and Alkynylsilanes

Facile Synthesis of Carbamoyl Fluorides via N-Carbamoylimidazole Activation

The untapped potential of carbamoyl fluorides for various chemico/biological applications is hampered by the scarcity of straightforward and benign methods for their synthesis. In this report, we disclose a novel mild three-step procedure that avoids exotic, corrosive, and highly toxic reagents. Briefly, commercially available secondary amines are carbamoylated with 1,1'-carbonyldiimidazole, followed by alkylation to improve nucleofugality, and exchange with inorganic KF. This procedure works on a gram scale without chromatographic purification. It is however limited to basic, sterically unhindered secondary amines without alkylation-prone functional groups.

One-Pot Transition-Metal-Free Synthesis of Alkynyl Amides

Alkynyl amides play crucial roles in organic synthesis in the production of bioactive compounds and valuable heterocycles. Despite numerous studies on their synthesis, challenges persist due to the necessity of harsh or hazardous conditions and the use of costly or unstable reagents. Herein, we present a one-pot method for the synthesis of all three bonds of the alkyne under transition-metal-free conditions. An important feature of this chemistry is the use of readily available feedstock chemicals, such as methyl esters and acetamides. This approach offers efficient access to a wide range of aryl and alkyl alkynyl amides and demonstrates excellent tolerance towards various functional groups in a sustainable and cost-effective manner.

B12-Catalyzed Carbonylation of Carbon Tetrahalides: Using a Broad Range of Visible Light to Access Diverse Carbonyl Compounds

Visible-light-driven organic synthesis is a green and sustainable method for producing fine chemicals and is highly desirable at both laboratory and industrial scales. In this study, we developed a broad-range (including the red region) visible-light-driven carbonylation of CCl4, CBr4, and CBr3F with nucleophiles, such as amines and alcohols, using a B12-Mg2+/TiO2 hybrid catalyst. Carbonyl molecules such as ureas, carbamates, carbonate esters, and carbamoyl fluorides were synthesized with high selectivity and efficiency under mild conditions. Diffuse reflectance UV-vis spectroscopy, femtosecond time-resolved diffuse reflectance spectroscopy, and density functional theory calculations revealed the reaction mechanism is a combination of SN2 and single-electron transfer. This is a rare example of a low-energy, red-light-driven photocatalysis, which has been a highly desired organic reaction in recent years. We believe that this study provides a general platform to access diverse carbonyl molecules and could promote photocatalytic carbonylation reactions on a pilot scale.

Pd-catalyzed Suzuki-type cross-coupling of 2-pyridyl carbamoyl fluorides

We describe a palladium-catalyzed Suzuki-type cross-coupling reaction of 2-pyridyl carbamoyl fluorides with boronic acids, which provides entry to medicinally relevant pyridyl amides. Mechanistic studies, including the synthesis and reactivity of carbamoyl Pd-F complexes, reveal the importance of both the fluoride electrophile and nitrogen directing group for aiding reactivity.

eFluorination for the Rapid Synthesis of Carbamoyl Fluorides from Oxamic Acids

In this letter, we disclose the anodic oxidation of oxamic acids in the presence of Et3N·3HF as a practical, scalable, and robust method to rapidly access carbamoyl fluorides from readily available and stable precursors. The simplicity of this method also led us to develop the first flow electrochemical preparation of carbamoyl fluorides, demonstrating scale-up feasibility as a proof of concept.

Expanded Access to Fluoroformamidines via a Modular Synthetic Pathway

Fluoroformamidines are an underutilized and understudied functional group despite combining two of the most highly prized elements in drug design: nitrogen and fluorine. We report a practical and modular synthesis of fluoroformamidines via the rearrangement of in situ-generated amidoximes. High yields in just 60 s at room temperature highlight the efficiency of this protocol. Furthermore, fluoroformamidines proved to be useful intermediates in the synthesis of diverse ureas and carbamimidates.