Time‐Economical Synthesis of Bis‐Spiro Cyclopropanes via Cascade 1,6‐Conjugate Addition/Dearomatization Reaction of para‐Quinone Methides with 3‐Chlorooxindoles

Abstract

A spirocyclopropanation of para-quinone methides with 3-chlorooxindoles that proceeds via cascade 1,6-conjugate addition/dearomatization reaction has been established, leading to a novel class of bis-spiro compounds in a concise, rapid, and practical manner. This transformation could be completed [a] J.

Catalytic Stereoselective Multicomponent Reactions for the Synthesis of Spiro Derivatives: Recent Progress

“…Zhao and colleagues performed a rapid spirocyclopropanation reaction with 3‐chlorooxindole and p ‐quinone methides at ambient reaction temperature (Scheme 36). [128] The target products are obtained by cascade 1,6‐conjugate addition followed by dearomatization with 1,5‐diazabicyclo[4.3.0]non‐5‐ene (Cat.29) in THF. Control experiments suggest an initial deprotonation of 3‐chloroxindole with a base.…”

“…Synthesis of bis-spiro cyclopropanes reported by Zhao and coworkers. [128] Scheme 37. Synthesis of coumarin/indandione-derived spirocyclopentanes reported by Lin and co-workers.…”

“…This first section is organized by the type of Michael cascade cyclization reactions, i. e., Michael spiro‐cyclization, [94–98] Michael/ N ‐hemiketalization or alkylation reaction, [99–103] Michael–Michael aldol reaction, [104–107] double Michael addition cyclization reaction, [108–110] and oxa/aza Michael cascade reaction [111–113] . The second part of this review is devoted to stereoselective multicomponent cycloaddition reactions, [114–121] and the third section contains diastereoselective approaches [122–135] and some miscellaneous reactions [136–140] to form spiro‐hetero/carbocycles.…”

Copper-Catalyzed Cascade Annulation of o-Hydroxyphenyl Propargylamines with Pyrazolin-5-ones to Access Pyrano[2,3-c]pyrazoles

“…Although there are several ways to access pyrano­[2,3- c ]­pyrazoles, the exploration of novel and simple synthetic methods remains highly desirable. In line with our ongoing interest in pyrazolone derivatives and QMs, we envisioned that the treatment of o -HPPAs with pyrazolones would result in facile 1,4-addition/intramolecular annulation in the presence of an appropriate catalyst, thus enabling the discovery of valuable new transformations and construction of pyrano­[2,3- c ]­pyrazoles in a simple manner (Scheme c). Herein, we report an efficient Cu­(OTf) 2 -catalyzed cascade reaction of pyrazolin-5-one with o -HPPAs, giving a series of pyrano­[2,3- c ]­pyrazoles in a short time.…”

Syntheses and Applications of Spirocyclopropyl Oxindoles: A Decade Review

“…[ 47 ] Zhao et al, devised a DBN‐catalysed protocol to furnish cyclohexadienones‐fused spirocyclopropyl oxindoles 93 by the reaction of 10 with p ‐QMs 92 (Scheme 29). [ 48 ] From the mechanism point of view, DBN initiates the reaction by deprotonation to generate carbanion intermediate 94 . 1,6‐Conjugate addition of 92 with intermediate 94 leads to the formation of second 3,3‐disubstituted oxindole intermediate 95 , which upon subsequent intramolecular nucleophilic substitution (S N 2‐type) produces the desired product 93 .…”