Related Experiment Video
Updated: Sep 10, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Oxonium/Sulfonium Ylide Rearrangements to Access Chromenes and Thiochromenes: Concerted or Stepwise Pathway?
Kajal B Meher1, Onkar S Bankar1, Hrishik Mukherjee1
1Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra, 411008, India.
Abstract:
Dirhodium(II)-catalyzed regio-divergent intramolecular rearrangement of oxonium and sulfonium ylides, generated from diazo arylidene succinimides (DAS), has been achieved at room temperature. Allyloxy-substituted DAS derivatives were strategically designed and synthesized to explore their reactivity under metal catalysis. The transformation is proposed to proceed via oxonium ylide intermediate, followed by [1,2]- and [1,4]-shifts, leading to the chromene framework. This strategy was further extended to thioallyl-substituted DASs to access thiochromenes under mild reaction conditions. For the first time, intramolecular rearrangement has been explored on DAS derivatives to synthesize bioactive chromene and thiochromene scaffolds.
More Related Videos
10:42Preparation of N-2-alkoxyvinylsulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
12:27Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
Related Concept Videos
Preparation and Reactions of Sulfides
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
SN1 Reaction: Mechanism
Firstly, the haloalkane ionizes to generate a carbocation intermediate and a halide ion. This heterolytic cleavage is highly endothermic with large activation energy. The ionization of the substrate, facilitated by a...
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide