A new facile way for the preparation of 3-formylcoumarins

Abstract

Abstract3-Formylcoumarins 2 are formed as single products in high yields upon reduction of 3-cyanocoumarins 1 with Raney nickel in formic acid. The starting materials 1 are easily accessible by Knoevenagel condensation of commercially available salicylaldehydes.

Synthesis of Coumarin‐Thiazolidine‐2,4‐dione‐Pyrazole Hybrids as Epidermal Growth Factor Receptor (EGFR)‐Targeted Agents

“…The entire synthesis of targeted coumarine‐thiazolidine‐2,4‐dione‐pyrazole hybrids ( 5 a – 5 o ) was shown in Scheme 1. In the first step, the reaction of 7‐methoxy‐2‐oxo‐2H‐chromene‐3‐carbonitrile ( 1 ) with Raney‐Ni using HCOOH at 90 0 C after 1.5 hours provided the 7‐methoxy‐2‐oxo‐2H‐chromene‐3‐carbaldehyde ( 2 ) [29] . Later, the piperidine promoted Knoevengal condensation reaction between 2 and thiazolidine‐2,4‐dione in methanol after 20 hours afforded the intermediate (Z)‐5‐((7‐methoxy‐2‐oxo‐2H‐chromen‐3‐yl)methylene)thiazolidine‐2,4‐dione ( 3 ) [30] .…”

“…In the first step, the reaction of 7-methoxy-2-oxo-2H-chromene-3carbonitrile (1) with Raney-Ni using HCOOH at 90 0 C after 1.5 hours provided the 7-methoxy-2-oxo-2H-chromene-3-carbaldehyde (2). [29] Later, the piperidine promoted Knoevengal condensation reaction between 2 and thiazolidine-2,4-dione in methanol after 20 hours afforded the intermediate (Z)-5-((7methoxy-2-oxo-2H-chromen-3-yl)methylene)thiazolidine-2,4-dione (3). [30] Then, the intermediate 3 was subjected to Nalkynylation using propargyl bromide in the presence of K 2 CO 3 in THF at 65 0 C for 9 hours to yield (Z)-5-((7-methoxy-2-oxo-2Hchromen-3-yl)methylene)-3-(prop-2-yn-1-yl)thiazolidine-2,4-dione (4).…”

Synthesis, antioxidant effectiveness, and docking study of new benzothiazolyl‐chromenone‐based fluorophores

“…The mixture was then filtered and washed with warmed 100 ml ethyl acetate and was evaporated using a rotary evaporator. The resulting oily yellow liquid was purified and concentrated with dichloromethane, and the resulting 2a-c solids were precipitated and crystallized from ethanol [15].…”

“…For use in photonic and pharmacological applications, the good electron-withdrawing nitro-benzothiazole moiety 5-nitrobenzo[d]thiazole (NBT) was formed to bind to the conjugated skeleton. The alkoxy-substituted benzothiazolyl-chromenone-based hybrids 3a-c included a characteristic conjugation between both chromenone and benzothiazole moieties, as shown in Scheme 1, in which 7-alkoxy-chromene-3-carbonitriles 1a-c were synthesized by condensation between 4-alkoxy-salicylaldehydes and malononitrile at room temperature and hydrolysis with intramolecular cyclization[14].In addition, the resultant derivatives 1a-c were reduced to the corresponding 7-alkoxy-chromene-3-carbaldehyde 2a-c through Raney nickel in the presence of formic acid at 90 C and according to a previous method detailed in the literature review with a 66% yield for derivative 2a after 2 h[15]. Here, 4-nitro-2-aminobenzenethiol and aryl-carbaldehyde in NaHSO 3 produced the corresponding 2-arylbenzo[d]thiazole with more than a 70% yield through a condensation process by refluxing in EtOH[16].Moreover, the structures of benzothiazolyl-chromenone-based fluorophore hybrids 3a-c were derived from their spectral analysis data.…”