Related Experiment Video
Updated: Sep 12, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Regiodivergent Synthesis of Eight-Membered Benzosilacycles via Palladium-Catalyzed Alkenyl C(sp2)-H Activation
Xiaoqian Yu1, Danni Wang1, Yangyang Li1
1College of Chemistry, Pingyuan Laboratory, Zhengzhou University, Zhengzhou 450001, China.
Abstract:
Herein we report a general and efficient method for the regiodivergent synthesis of medium-sized eight-membered aryl- and alkenylsilacycles via a palladium-catalyzed alkenyl C(sp2)-H activation/ring expansion cascade. This protocol features a broad substrate scope regarding o-bromostyrenes and silacyclobutanes, excellent regioselectivities, mild reaction conditions, and scalability. Control experiments revealed that the regioselectivity of this reaction is dictated by the synergistic interplay between the electronic nature of the α-substituent in the substrate and the precisely tuned catalytic system. The synthetic potential of this method is further exemplified by the versatile downstream transformations.
Related Concept Videos
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Cycloaddition Reactions: Overview
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
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.

![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)