Synthesis of some novel spiro substituted pyrido[2,3-c]coumarins by exploring ‘tertiary amino effect’ reaction strategy

An Efficient Synthesis of Pyrido[3, 2‐c]coumarins under Microwave Irradiation in Solvent‐Free Conditions

“…The reaction was initiated with the preparation of the key starting material 4-chloro-3-formylcoumarin 2 (R 1 = H) from 4hydroxycoumarin 1 (R 1 = H) by treatment with Vilsmeier reagent following the existing reaction protocol we reported earlier. [17] 4-Chloro-3-formylcoumarin 2 (R 1 = H) so obtained was then reacted initially with equimolar amounts of acetophenone 3 (R 2 = H) in the presence of three equivalent of ammonium acetate in acetonitrile as well as in water under refluxed conditions, but the reaction did not occur in both the solvents (Entry 1-2). However, when the reaction was performed in DMF, DMSO and toluene at 120 8C provided very low yield of the product 4 a (Entry 3-5).…”

“…In continuation of our work on coumarins, in the present paper, we report the synthesis of some novel functionalized pyrido[3, 2‐ c ]coumarins by exploring the reactivity of 4‐chloro‐3‐formylcoumarins 2 ( β ‐halo aldehydes) obtained from 4‐hydroxycoumarins 1 , with aryl methyl ketones 3/ ethyl acetoacetate 5/ ethyl cyanoacetate 8 in the presence of ammonium acetate under microwave (Microwave Reactor) in solvent‐free condition which afforded after work‐up the pyrido[3, 2‐ c ]coumarins 4/6/9 in excellent yields (Scheme ).…”

A Concise Review on Pyridocoumarin/Azacoumarin Derivatives: Synthesis and Biological Activity

“…An interesting ‘tertiary amino effect’ reaction strategy was described by Borah et al . to synthesise some novel spiro substituted pyrido[2,3‐ c ]coumarins 107 & 109 where 4‐hydroxy coumarin 51 was used as starting material.…”

Zinc chloride catalyzed multicomponent synthesis of pyrazolopyridocoumarin scaffolds

“…The MCRs have additional benefits of being selective, time-saving, convergent, atom economy and playing an important role in modern synthetic methodology. [1][2][3][4][5][6][7][8][9][10][11][12][13] Fused polyheterocycles are an important class of organic molecules [14][15][16][17][18] because of their widespread applications ( Figure 1) as pharmaceuticals (A, B, C & D), [19][20][21] photosensitizer (E) 20,21 and fluorescent dye (F). 22 Coumarin nucleus fused with pyridine rings have received increasing attention due to their photophysical properties 23 and potential biological activities such as antimicrobial, 24 antiosteoporotic, 25 antiinflammatory 21 and analgesic.…”