Borrowing and Returning Oxygen Atom in Trifluoroacetic Anhydride Transfer to Nitrones: A Versatile Route for the Synthesis of N -Trifluoroacetyl Amides

Electrochemical Strategy for the Radical Fluoroacetylation of Sulfoximines from Fluorinated Alkyl Carboxylic Acids

The integration of trifluoroacetyl (CF3CO) groups into organic skeletons is a key research topic in synthetic chemistry given their significant potential to boost biological activity. Despite recent developments of strategies for incorporating trifluoroacetyl moiety via trifluoroacetyl radical intermediates, the practical utilization of inexpensive and readily available trifluoroacetic acids as trifluoroacetyl radical sources has not yet been developed. Herein, an electrochemical strategy has been employed to achieve the radical deoxygenative transformation of trifluoroacetic acids directly with the assistance of PPh3. The obtained trifluoroacetyl radicals are then coupled with sulfoximine species, thus enabling the synthesis of N-trifluoroacetylated sulfoximines. Additionally, other fluorinated alkyl carboxylic acids, including perfluoro-, difluoro-, and trifluoromethylcarboxylic acids, can also be efficiently utilized under these conditions, leading to their corresponding acylated sulfoximines. Moreover, the trifluoroacetylation of drug-based molecules and the easy execution of scale-up experiments highlight the applicability of this protocol.

Acyclic Twisted Amides

In this contribution, we provide a comprehensive overview of acyclic twisted amides, covering the literature since 1993 (the year of the first recognized report on acyclic twisted amides) through June 2020. The review focuses on classes of acyclic twisted amides and their key structural properties, such as amide bond twist and nitrogen pyramidalization, which are primarily responsible for disrupting nN to π*C═O conjugation. Through discussing acyclic twisted amides in comparison with the classic bridged lactams and conformationally restricted cyclic fused amides, the reader is provided with an overview of amidic distortion that results in novel conformational features of acyclic amides that can be exploited in various fields of chemistry ranging from organic synthesis and polymers to biochemistry and structural chemistry and the current position of acyclic twisted amides in modern chemistry.

Self-Catalyzed Rapid Synthesis of N-Acylated/N-Formylated α-Aminoketones and N-Hydroxymethylated Formamides from 3-Aryl-2H-Azirines and 2-Me/Ph-3-Aryl-2H-Azirines

A rapid and effective method has been established for the synthesis of N-acylated α-aminoketone derivatives by the reaction of 3-aryl-2H-azirines and highly substituted 2-Me/Ph-3-aryl-2H-azirines with various carboxylic acids under ambient air within 10 min at room temperature. N-Trifluoroacetylated α-aminoketones with different substituents have been reported in the presence of trifluoroacetic acid. This protocol is equally effective to synthesize N-formylated α-aminoketone and N-hydroxymethylated formamide derivatives.

Perfluorocarboxylic Anhydrides Triggered Cyclization: Access to 4-Perfluoroalkylpyridines

A double nucleophilic addition-cyclization-elimination cascade is developed, that allows various 2,6-diaryl-4-perfluoroalkylpyridines to be synthesized in one step from easily available enamides and perfluorocarboxylic anhydrides. The procedure is also operationally simple and scalable and provides access to the facial construction of 4-fluoroalkylpyridines, which are of great interest in medicinal chemistry.

Synthesis of 3-(tri/difluoromethyl)-1H-1,2,4-triazol-5(4H)-ones via the cyclization of hydrazinecarboxamides with tri/difluoroacetic anhydride

An efficient method for the synthesis of structurally diverse 4-aryl-3-(tri/difluoromethyl)-1H-1,2,4-triazol-5(4H)-ones through the cyclization of hydrazinecarboxamides with tri/difluoroacetic anhydride is presented. The method is simple and environmentally benign, providing tri/difluoromethylated 1,2,4-triazol-5(4H)-ones in moderate-to-good yields. A mechanism is proposed to proceed via a tandem reaction of tri/difluoroacetylation, nucleophilic addition and water elimination. Some of these compounds exhibit promising insecticidal activities.