Photoinduced Cascade C–N/C═O Bond Formation from Bromodifluoroalkyl Reagents, Amines, and H₂O via a Triple-Cleavage Process

Abstract

A green, sustainable, and straightforward method for the synthesis of unsymmetrical oxalamides via photoinduced C–N/CO bond formation of bromodifluoroacetamide, amine, and H2O through a triple-cleavage process has been developed. In addition, this approach also provides access to the known bioactive compounds, and a feasible reaction mechanism is proposed. Moreover, the advantages of this transformation, including mild reaction conditions, a broad substrate scope, and operational simplicity, make this protocol attractive for further applications.

Visible light-mediated metal-free alkyl Suzuki–Miyaura coupling of alkyl halides and alkenylboronic acids/esters: a green method for the synthesis of allyl difluoride derivatives

“…In some cases, the formation of α-ketoamides was observed in our reaction system via photoinduced cascade N-dealkylation 27 /CvO bond formation 28 from ArCOCF 2 Br, tertiary amines, and H 2 O (for details, see the ESI †). To explore this unprecedented N-dealkylation process, several tertiary amines such as Et 3 N, TMEDA, N(Me) 2 Bn, 4-methylmorpholine, N(n-Pr) 3 , 1-phenylpyrrolidine, and DIPEA were selected to react with 2b or 2a, and the results are shown in Scheme 2d (see Fig.…”

Photoredox-Catalyzed Tandem Radical Cyclization/Hydroxylation for the Synthesis of 4-Hydroxyalkyl-3,3-difluoro-γ-lactams

“…For new compounds a6 , a21 , and a26 , the synthetic methods are described in the following sections. For other known compounds of a , see refs , , and .…”

Photoredox-Catalyzed Redox-Neutral Decarboxylative C–H Acylations of Coumarins with α-Keto Acid

“…Compared with other acyl sources, α-keto acids have become a better choice for the synthesis of related ketone derivatives because of their low cost, stability, easy preparation, and high reactivity. − The greener characteristic of the coproduct formed in reactions using α-keto acid (only CO 2 ), together with its versatility as a building block in catalytic organic synthesis, makes it a candidate for being a green acylating agent and an alternative to acyl chloride or other acyl transfer reagents. Photoredox catalysis has been regarded as an eco-friendly and effective strategy due to its convenience, availability, and safety. − Upon irradiation with visible light, conversion of α-keto acids into acyl radicals can be achieved via a single-electron transfer (SET) process by photocatalytic oxidation and subsequent decarboxylation. − However, in most cases, an additional oxidant or additive was essential. From the perspective of green chemistry, the development of the C–H acylation reaction under oxidant and additive free conditions is highly desirable.…”