Highly stereoselective spirocyclopropanation of various diazooxindoles with olefins catalyzed using Ru(ii)-complex

Abstract

Optically active spirocyclopropyloxindole derivatives were efficiently synthesized from diazooxindoles and olefins in the presence of a Ru(ii)-Pheox catalyst.

Stereoselective synthesis and applications of spirocyclic oxindoles

“…35 Iwasa used chiral Ru(II) complex 7 to generate spirocyclopropyl oxindoles with high ee. 36 Ashfeld reported a cyclopropanation/ring expansion cascade reaction between 3-diazooxindoles and vinyl isocyanate, in the case when the temperature was reduced from 50°C to rt, the cyclopropane intermediate could be isolated as one diastereomer. 37 In 2014, Lu and Xiao showed a [3 + 2]-cycloaddition between 3-ylideneoxindoles and in situ generated 2,2,2-trifluorodiazoethane could afford a pyrazoline which upon heating under reflux in toluene would ring contract to afford 3,3′-cyclo-Fig.…”

Syntheses and Applications of Spirocyclopropyl Oxindoles: A Decade Review

“…The high enantioselectivity was a result of π–π interaction between oxindole and the indane ring of ligand VII allowing olefin to approach from only one side. [ 35 ]…”

Self-Supported Chiral Dirhodium Organic Frameworks Enables Efficient Asymmetric Cyclopropanation

“…Dirhodium complexes are bimetallic compounds with one Rh–Rh bond and four bridging ligands at equatorial positions, displaying a unique paddle-wheel structure. − By virtue of the distinct structure and high stability, they exhibited versatile and powerful catalytic properties for a diverse array of carbine transformations of diazocarbony compounds, including cyclopropanation, C–H activation, olefins aziridination, and ylide formation. − The variety of reactions has made dirhodium complexes extremely attractive in the syntheses of important organic compounds as active pharmaceutical ingredients. − In this context, spiro -cyclopropyloxindoles constitute a unique motif of heterocycles with potential applications as potent HIV inhibitor, antitumor agent, and useful building blocks, which can be synthesized by cyclopropanation of diazooxindoles with alkenes employing dirhodium, ruthenium, mercury, and gold catalysts. − Compared to ruthenium, mercury, and gold catalysts, the dirhodium catalysts are more reactive toward alkyl-substituted alkene substrates in the cyclopropanation reaction. − However, the unsatisfactory catalyst recyclability and reusability of homogeneous dirhodium catalysts are the primary restricting factors for their practical application in industrial processes.…”