Ultrasonic Assisted Facile Synthesis of N‐Arylamides Using Nitriles and 1‐Aryltriazenes Precursors Promoted by Brønsted Acidic Ionic Liquid under Metal‐Free Conditions

Abstract

Ultrasonic assisted rapid and eco-friendly synthesis of an array of N-aryl amides is accomplished in good to better yields employing Brønsted acidic ionic liquid as promoter. The similar reaction also progressed under conventional mode of heating,but at relatively slower rate. Structurally varied 1-aryltriazenes and aliphatic/aromatic nitriles are evaluated in this metal-free approach and demonstrate the versatility of this protocol. A better functional group tolerance, mild reaction conditions, ultrasonic assistance, short reaction time, reuse and recycle of Brønsted acidic ionic liquid makes this method more practical and efficient to the existing methods.

Ultrasonication Assisted α‐Arylation of N‐heteroarenes Employing 1‐Aryltriazenes Promoted by Brønsted Acidic Ionic Liquid under Aerobic Conditions

“…Initially, a model reaction was carried out using simple isoquinoline and 1‐(phenyldiazenyl)pyrrolidine ( 2 a ) as starting materials to investigate the feasibility of the reaction to achieve the formation of the desired product ( 3 i ). Different aryltriazenes were synthesized from the corresponding aromatic amines and various secondary amines by following the reported procedures [37j–l,38] and used further after recrystallization from suitable solvents. Various Brønsted Acidic Ionic Liquids (BAILs) were tested as promoters, while the ionic liquid either [BMIM][BF 4 ] or [BMIM][PF 6 ] as the reaction medium by varying the temperatures (Table 1, entries 1–18) to examine the reaction trends.…”

“…Owing to the distinct advantageous effects involved such as qucik dissolution, homogenisation, rate acceleration and intensification phenomenon, ultrasound (US) promoted organic synthesis in combination with ILs [35a] gained much consideration in the last few decades. Recently, we have reported N ‐arylation of amines, employing 1‐aryltriazenes as arylating sources mediated by ILs in combination with US [37k] . Thus, we thought to explore this sort of methodology for the complementary arylation of N ‐heteroarenes.…”

“…In continuation of our efforts towards developing efficient, green, and novel methodologies, [37a–i] we have previously reported C−C bond formation, [37j] C‐2 arylation of azoles, [37k] arylamides [37l] employing 1‐aryltriazenes as efficient coupling partners with aryl ethynes [ 37i] in different ionic liquid media. As part of our ongoing research program to promote green syntheses, we have developed a new methodology employing Brønsted Acidic Ionic Liquid (BAIL) as a promoter for the α‐arylation of N‐ heterocyclic substrates using 1‐aryltriazenes as arylating precursors (structures of various triazenes used in this study were given in the SI file, Figure S1), in the ionic liquid reaction medium under ultrasonication.…”

Tropylium‐BF4as Organocatalyst for Microwave‐assisted Beckmann rearrangement in [TMG][BF4]: One‐pot conversion of Ketones to Amides

“…Similarly, we have reported Ritter reaction pathway in ILs for the construction of amides from nitriles and in the synthesis of biarylamides [4f] . Further, amide synthesis was achieved by N ‐arylation of 1‐aryltriazenes in presence of various ionic liquids [4d] . With a keen interest in method development, we have reported the conversion of aldoximes to nitriles by employing tropylium tetrafluoroborate (Tp + BF − 4 ) as an organocatalyst [16] .…”

Microwave and Ultrasonic‐Assisted Synthesis of Highly Functionalized Carbazoles And Dibenzofurans from Biaryl‐Triazenes Promoted by Acidic Ionic Liquid

“…These conversions could be achieved under micro‐wave heating at lower temperatures and with shorter reaction times [25] . It has been documented well that ionic liquid has a great potential in exploring reactions in microwave [26] and ultrasonication owing to its unique and efficient absorption of energy from those sources [23e] …”