Syntheses and Applications of Spirocyclopropyl Oxindoles: A Decade Review

Abstract

Spirocyclopropyl oxindole represents an emerging framework by unique amalgamation of versatile 2‐oxindole motif and highly strained cyclopropane unit. This scaffold is remarkable for its diverse medicinal and synthetic applications. The present review delivers a comprehensive overview of the strategies to afford spirocyclopropyl oxindoles and their potential synthetic transformations. The syntheses of spirocyclopropyl oxindoles have been described based on the type of precursors, including isatin, 3‐alkenyl oxindole, diazooxindole, oxindole, and 3‐chlorooxindole. Besides, the utility of different cyclopropanation reagents like sulfur ylide, MBH‐carbonate, carbenoid, vinyl selenone, etc. have also been emphasized. Furthermore, various ring‐expansion/opening reactions of spirocyclopropane oxindoles using dipolarophiles/nucleophiles have critically been illustrated.

Applications of Oxone® in Organic Synthesis: An Emerging Green Reagent of Modern Era

“…Oxindoles are naturallyoccurring molecules having applications in material as well as biological sciences. The development of simple, efficient, economical and environmentally benign methods for carbonyl group‐containing oxindoles are of specific interest due to their utility in pharmaceuticals, biochemistry, materials science & technology etc [97,98] . Keeping the importance of these systems in mind, Guo's group exposed a novel approach for carboacylation/arylation of N ‐arylacrylamides 123 in the presence of KHSO 5 via the oxidative cleavage of C−C bond and formation of a new C−C bond (Scheme 36).…”

Visible‐Light‐Mediated Ring‐Opening Reactions of Cyclopropanes

“…Due to the ring strain (approximately 28 kcal/mol), cyclopropanes are widely used as the precursor for the synthesis of various carbocycles, heterocycles, macromolecules and for other transformations by ring-opening reactions. [29][30][31][32][33][34][35][36][37][38] There exist various methods for the ring-opening transformations of cyclopropanes. [39][40][41][42][43][44][45] The pioneering ring-opening of cyclopropane was reported in 1966 by Schaafsma and co-workers.…”

Divergent Metal-Free [4 + 2] Cascade Reaction of 1-Indanylidenemalononitrile with 3-Benzylidenebenzofuran-2(3H)-one: Access to Spiro-dihydrofluorene-benzofuranone and Axially Chiral Fluorenylamine-phenol Derivatives

“…As a result, enormous spirocyclic compounds were designed and synthesized to achieve this skeleton . However, most of the reported synthetic methodologies mainly focus on the construction of spirooxindoles, spiroindenes, spirobenzofurans, and others (Scheme a). On the contrary, it has not drawn enough attention for the construction of fluorene-based spirocyclic backbones.…”