What is it about?
This study uses density functional theory (DFT) calculations to reveal how magnesium carbenoids insert into unreactive C–H bonds to form cyclopropanes. The calculations show that the reaction proceeds through an SN2-like transition state, in which the C–H bond acts as a nucleophile and attacks the electrophilic carbenoid carbon. The study also explains why chlorine-substituted magnesium carbenoids readily undergo C–H insertion, whereas the corresponding alkoxy- and thio-substituted compounds do not.
Featured Image
Photo by Alex on Unsplash
Why is it important?
Magnesium carbenoids are versatile reactive intermediates that can form carbon–carbon bonds through unusual transformations, including C–H insertion. However, their high reactivity has made it difficult to determine how these reactions occur experimentally. This work provides a molecular-level explanation of the reaction mechanism and identifies carbene character as a key factor controlling C–H insertion reactivity. These insights can help guide the design of new carbenoid-mediated synthetic reactions.
Perspectives
Our calculations revealed that magnesium carbenoids undergo 1,3-C–H insertion through an unexpected SN2-like pathway rather than a free-carbene mechanism. We also found that the degree of carbene character plays a decisive role in determining the feasibility of C–H insertion. We hope these mechanistic insights will support the development of new carbenoid reactions and deepen our understanding of their unique reactivity.
Associate Professor Tsutomu Kimura
Read the Original
This page is a summary of: Mechanism of magnesium carbenoid 1,3-C-H insertion: a DFT study, Journal of Physical Organic Chemistry, April 2015, Wiley,
DOI: 10.1002/poc.3440.
You can read the full text:
Resources
Contributors
The following have contributed to this page
