Synthesis of Hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1′‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones] from 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione Using Fe₃O₄@Cu(OH)_x as a Nanocatalyst

Abstract

The tricyclic isatin, 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione, undergoes three‐component, one‐pot reactions with 1‐aryl‐3‐methylpyrazole‐5‐amines and cyclohexane‐1,3‐diones producing hexacyclic spiro products, hexahydrospiro[pyrazolo[3,4‐b]quinoline‐4,1‐pyrrolo[3,2,1‐ij]quinoline‐2′,5(1H,4′H)‐diones]. Comparable spiro condensation products are also obtained using 4‐hydroxy‐2H‐1‐benzopyran‐2‐one in place of cyclohexane‐1,3‐diones.

Three-component synthesis of novel spiro[4H-pyran-3,3′-oxindoles] using 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1,2-dione

“…The route is applicable to a range of structurally varied starting components, as illustrated in our previous papers; Figure 1 shows a selection of the products from those studies. 8 Herein, we describe a further extension of this methodology using a new combination of three components. 3) is readily prepared from 1,2,3,4-tetrahydroquinoline by reaction with oxalyl chloride and then Friedel-Crafts ring closure of the resulting amide-acid chloride with aluminium trichloride.…”

“…9 Like simpler isatins, the ketone-carbonyl of the -keto-amide unit is especially electrophilic and this property is at the basis of the work reported here, and our previous results. 8 Cyanomethyl aryl ketones 4 were made according to the literature via methyl bromination of acetophenones and then displacement of bromide with cyanide. 10 When the tricyclic isatin 3 is reacted with two other components, both of which can in principle take part in a Knoevenagel condensation, and both of which can provide a nucleophilic enol/enolate, 3,3'-spirocyclic products result.…”

“…10 When the tricyclic isatin 3 is reacted with two other components, both of which can in principle take part in a Knoevenagel condensation, and both of which can provide a nucleophilic enol/enolate, 3,3'-spirocyclic products result. 8 These must be the result of two steps involving first, a Knoevenagel condensation and then an addition to the conjugated system thus produced and finally cyclisation. Scheme 1 and Table 1 summarize the three-component one-pot syntheses that we report here, involving isatin 3, a cyanomethyl aryl ketone 4 as the second component and malononitrile 5 (X = CN) or ethyl cyanoacetate 5 (X = CO2Et), as the third, giving spiro-products 6.…”

Synthesis of novel spiro‐fused pyrazolo[4′,3′:5,6]pyrido[2,3‐d]pyrimidines

“…For the most part, such structures have been prepared (eg, 1,2) starting from an isatin, for example, isatin itself (1 H ‐indole‐2,3‐dione) ( 2 ). In our work, 8 on the synthesis of spiro‐3,3′‐oxindoles, we have developed a three‐component one‐pot route using 5,6‐dihydro‐4 H ‐pyrrolo[3,2,1‐ ij ]quinoline‐1,2‐dione ( 3 ), as the isatin component. The route has proved applicable to a range of structurally varied starting components, and in this article, we describe a further extension using new combinations of starting components which led us to some pyrazolo[4′,3′:5,6]pyrido[2,3‐ d ]pyrimidine 4 derivatives, specifically, 4,9‐dihydro‐1 H ‐pyrazolo[4′,3′;5,6]pyrido[2,3‐ d ]pyrimidine‐5,7(6 H ,8 H )‐diones, with an associated spiro‐3,3′‐oxindole attachment at C‐4 (Figure 1).…”