Reactions of 4-chloro-3-formyl-coumarin with primary amines

Abstract

the triethylamine by anhydrous sodium acetate in the reaction of chlorocoumarin with 2-aminopyridines leads to the formation of the condensed benzopyranopyridopyrimidine system as a result of nucleophilic attack of the amino group by the chlorine atom at position 4.

Crystal structure of 1-(4-fluorophenyl)chromeno[4,3-c]pyrazol-4(1H)-one, C16H9FN2O2

“…The torsion angle N2-N1-C13-C18 is 67.2(2)°is similar to that published in [1] for the molecule without fluorine at position 4ofthe phenyl ring (73.1(6)°). Also the other bond angles and bond lengths do not show significant differences to that described in [1]. …”

Metal‐ and Catalyst‐Free One‐Pot Cascade Coupling of α‐Enolic Dithioesters with in situ Generated 4‐Chloro‐3‐formylcoumarin: Access to Thioxothiopyrano[3,2‐c]chromen‐5(2H)‐ones

“…[14] The in situ generation of 4-chloro-2-oxo-2H-chromene-3-carbaldehyde 2 has been done by treating 4-hydroxy-2H-chromen-2-one with POCl 3 /DMF mixture as formylating reagents under Vilsmeier conditions. [15] α-Enolic dithioesters 3 are not commercially sourced, and were synthesized in good yields following the reported procedure. [16] To an ice-cooled stirred solution of 4hydroxy-2H-chromen-2-one (1) (0.25 mmol, 1 equiv.)…”

A Simple Efficient Procedure for the Synthesis of Benzopyrano[2,3‐c]pyrazoles

“…The development of efficient methods for the synthesis of this class of condensed heterocycles is thence of growing interest. However, in contrast to the extensive work reported on benzopyrano[4,3‐ c ]pyrazoles , the work on compounds bearing benzopyran and pyrazole groups fused at the 2,3‐positions was scanty. The main method reported for their synthesis was that condensed arylhydrazines with 4‐hydroxy coumarins acylated in the 3‐position, but it was limited by low overall yield and poor accessibility to required starting materials .…”

“…However, in contrast to the extensive work reported on benzopyrano[4,3‐ c ]pyrazoles , the work on compounds bearing benzopyran and pyrazole groups fused at the 2,3‐positions was scanty. The main method reported for their synthesis was that condensed arylhydrazines with 4‐hydroxy coumarins acylated in the 3‐position, but it was limited by low overall yield and poor accessibility to required starting materials . More recently, Gorobets et al have reported that refluxing of 3‐amido hydrazonocoumarins in DMF in the presence of acetic anhydride allowed the synthesis of the corresponding benzopyrano[2,3‐ c ]pyrazoles, which can be also obtained in one pot under microwave conditions from 2‐iminocoumarin‐3‐carboxamides and hydrazines .…”