PTSA^.H₂O‐Catalyzed Reaction of 3‐Aminocoumarins and Phenylacetaldehydes: A Route to Access Various Pyrido(2,3‐c)coumarin Derivatives

Abstract

A number of pyrido(2, 3‐c)coumarin derivatives were accomplished from various 3‐aminocoumarins and phenylacetaldehydes in acetonitrile using 10 mol% p‐toluenesulfonic acid monohydrate (PTSA.H2O) as a catalyst. The protocol is an easy approach to synthesize a number of biologically important coumarin fused pyridine derivatives.

Facile access to 2‐amino‐4‐aryl‐5H‐chromeno[4,3‐b]pyridine‐3‐carbonitriles through a strategy of one‐pot Michael/cyclization reaction

“…Then, the influence of the amount of ammonium acetate on the model reaction was researched. When the amount of ammonium acetate was reduced, the product yield would be significantly reduced (Table 1, entry 15 and entries [23][24]. On the whole, the reaction proceeded most smoothly in ethanol at 70 C in the presence of 2 equiv.…”

“…Conventionally, the chromeno[4,3‐ b ]pyridine skeleton can be constructed from the three‐component reaction of 4‐aminocoumarin, aldehydes, malononitrile [18, 19] or other active methylene compounds [20, 21]. Furthermore, 4‐aminocoumarin can react with β‐carbonyl‐substituted 4 Н ‐chromenes [22], α‐azidochalcones [11], phenylacetaldehydes [23], 1,3‐diarylpropenes [24], β‐alkoxyvinyl trifluoromethyl ketones [13], with the produce of different chromeno[4,3‐ b ]pyridine derivatives. Similarly, the already existing chroman‐4‐ones [25, 26], or their intermediates formed in the reaction process [27], can be used for the preparation of chromeno[4,3‐ b ]pyridine skeleton.…”

p-Toluenesulfonic acid-promoted organic transformations for the generation of molecular complexity

“…Khan and co-workers have explored the route to access biologically important 65 coumarin fused pyridine derivatives in acetonitrile under reflux conditions. 66 In their approach, a variety of phenylacetaldehyde derivatives were reacted with 3-aminocoumarins containing 7-MeO, 8-EtO, 8-MeO, 6-Br, 6-Cl, 6,8-dichloro substituents in the presence of 10 mol% p -TSA, affording the desired pyrido(2,3- c )coumarin derivatives after simple workup procedures with satisfactory yields (Scheme 44). However, this protocol is not pertinent for other aliphatic aldehydes.…”

Double Brønsted Acidic Media Immobilized on Carbonized Sugarcane Bagasse (CSCB) as a New and Efficient Solid Acid Catalyst for the Synthesis of Coumarins, Dicoumarols and Xanthenes

“…Coumarin is a significant building block in natural products and organic synthesis, and a large number of efforts have been utilized to explore new synthetic strategies . The use of new catalytic systems for the synthesis of coumarins and the synthesis of new derivatives bearing coumarin building block are two main roads of researches on coumarins .…”

“…[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] Coumarin is a significant building block in natural products and organic synthesis, and a large number of efforts have been utilized to explore new synthetic strategies. [55][56][57] The use of new catalytic systems for the synthesis of coumarins [58] and the synthesis of new derivatives bearing coumarin building block are two main roads of researches on coumarins. [59] Recently, nanocatalysts [60] and magnetic catalysts [61] have been used to prepare coumarin and its derivatives.…”