Issue 21, 2024

Cascade reactions of HDDA-benzynes with tethered cyclohexadienones: strain-driven events originating from ortho-annulated benzocyclobutenes

Abstract

Intramolecular net [2 + 2] cycloadditions between benzyne intermediates and an electron-deficient alkene to give benzocyclobutene intermediates are relatively rare. Benzynes are electrophilic and generally engage nucleophiles or electron-rich π-systems. We describe here reactions in which an alkene of a tethered enone traps thermally generated benzynes in a variety of interesting ways. The number of atoms that link the benzyne to C4 of a cyclohexa-2,5-dienone induces varying amounts of strain in the intermediates and products. This leads to a variety of different reaction outcomes by way of various strain-releasing events that are mechanistically intriguing. This work demonstrates an underappreciated class of strain that originates from the adjacent fusion of two rings to both C1–C2 and C2–C3 of a benzenoid ring – i.e.ortho-annulation strain’. DFT computations shed considerable light on the mechanistic diversions among various reaction pathways as well as allow more fundamental evaluation of the strain in a homologous series of ortho-annulated carbocycles.

Graphical abstract: Cascade reactions of HDDA-benzynes with tethered cyclohexadienones: strain-driven events originating from ortho-annulated benzocyclobutenes

Supplementary files

Article information

Article type
Edge Article
Submitted
24 Jan 2024
Accepted
16 Apr 2024
First published
30 Apr 2024
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2024,15, 8181-8189

Cascade reactions of HDDA-benzynes with tethered cyclohexadienones: strain-driven events originating from ortho-annulated benzocyclobutenes

B. S. Chinta, D. S. Sneddon and T. R. Hoye, Chem. Sci., 2024, 15, 8181 DOI: 10.1039/D4SC00571F

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