Syntheses of angular condensed ring systems combining a benzodiazepinic, or benzothiazepinic, and a coumarinic moiety

Synthesis and Chemical Reactivity of the Novel 4‐Hydroxy‐6‐methyl‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde

“…On the other hand, condensation of carboxaldehyde 4 with 2‐aminophenol gave the Schiff base 12 , which exist in the enol‐imine form rather than the keto‐enamine tautomeric form (Scheme ) . The 1 H NMR spectrum of compound 12 revealed typical signals to the enol‐imine structure indicating that this condensate is an exception of the aforementioned results.…”

“…Whereas, the reaction of carboxaldehyde 4 with 2‐aminothiophenol afforded 3‐(1,3‐benzothiazol‐2‐yl)‐4‐hydroxy‐6‐methyl‐2 H ‐pyrano[3,2‐ c ]quinoline‐2,5(6 H )‐dione ( 14 ) (Scheme ). The latter reaction may occur via the formation of the non‐isolable Schiff base intermediate 13 , which underwent in situ an intramolecular cycloaddition of SH group onto the azomethine bond followed by dehydrogenation leading to the final product 14 (Scheme ) . The spectrum of compound 14 showed only eight aromatic protons without any traces of the azomethine proton, indicating the absence of Schiff base 13 .…”

Synthesis of N1‐substituted coumarino[4,3‐c] pyrazoles

“…Different biological activity of the coumarins fused with other heterocycles in 3,4-positions [5][6][7][8][9][10][11][12][13] prompted the synthesis of coumarino [4,3-c]-N 1 -substituted pyrazoles. Woulfson and Zhurin [14] reported the synthesis of coumarino [4,3-c]-N 1 -phenyl-3-methylpyrazoles by cyclizing the phenylhydrazones of 3-acetyl-4-hydroxycoumarins using p-toluensulphonic acid.…”

Synthesis of [1]Benzopyrano[4,3-b]pyrrol-4(1H)-ones from 4-Chloro-3-formylcoumarin

“…The varied biological activity of the coumarins fused with other heterocycles, has encouraged research with regard to the procedures and substrates, which due to their versatility, allow the easy preparation of broad families of these compounds. Thus, for example, the 4-chloro-3-formylcoumarin (1) and the 4-azido-3-formylcoumarin (2) have been used in the synthesis of benzopyranones [3,4] fused to pyrazoles, isoxazoles, thiophenes and other heterocycles. [2][3][4][5][6][7][8][9][10][11] Among these the [1]benzopyrano [4,3-b]pyrrol-4(1H)-ones which can be prepared by Fischer-Fink reactions are not found.…”

“…Thus, for example, the 4-chloro-3-formylcoumarin (1) and the 4-azido-3-formylcoumarin (2) have been used in the synthesis of benzopyranones [3,4] fused to pyrazoles, isoxazoles, thiophenes and other heterocycles. [2][3][4][5][6][7][8][9][10][11] Among these the [1]benzopyrano [4,3-b]pyrrol-4(1H)-ones which can be prepared by Fischer-Fink reactions are not found. This absence may be attributable to the apparently arbitrary behaviour of the 4-chloro-3formylcoumarin toward the a-amino functions, as we were able to confirm in our exploratory studies concerning these reactions (Scheme 1).…”