Sulfamic acid promoted expeditious and column chromatography free synthesis of functionalized spiro [indoline-3, 7′-pyrano [3, 2-c: 5, 6-c'] dichromene]-2, 6′, 8′-trione derivatives under reflux conditions

• Published in: Journal of molecular structure 2022-04, Vol.1253, p.132213, Article 132213
• Main Authors: Mal, Kajal, Mukhopadhyay, Chhanda
• Format: Article
• Language: English
• Subjects: Coloumn chromatography free; Excellent yields; Green solvent; Heterocyclic spiro compounds; Metal-free synthesis
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2021.132213

•An eco-friendly synthesis of biologically significant spirooxindoles derivatives.•Use of aqueous ethanol makes this methodology more superior to the existing one.•High to excellent yield (upto 96%) was found in shorter reaction time.•No metal catalyst is required.•The methodology requires no Coloumn chromatography to purify the products. Development of an expeditious and green protocol to access pharmaceutically relevant and diversely functionalized scaffolds, Spiro [indoline-3,7′-pyrano[3,2-c:5,6-c']dichromene]-2,6′,8′-trione, has been accomplished based on a pseudo three-component reaction between isatins and 4-hydroxycoumarin in presence of a low-cost and eco-friendly solid sulfamic acid catalyst in aqueous ethanol (1:1, v/v) under reflux condition. The significant features of this newly developed method are metal-free one pot synthesis, use of eco-friendly and cost-effective solvent and catalyst, no column chromatography involvement for isolation of the products, high to excellent yields, reusability of reaction media and gram scale synthetic applicability. [Display omitted]