Regioselectivity Patterns in Radical Cyclization of Diosphenol Derivatives with Different Ring Size: A Combined Experimental and DFT Study

Esra Boz, Hafize Özcan, Ömer Zaim*, Nurcan Tüzün*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Radical cyclization reactions are still a challenging field in synthetic organic chemistry. Herein, the radical reactions of 6- and 7-membered diosphenol derivatives (tropolone) with a significant difference in reactivity, ring size, aromaticity and stability were investigated. While the former produces a mixture of products including oxabicycloalkanones, the experimental work performed herein resulted with a single 2-(3-hydroxypropyl)cyclohepta-2,4,6-trienone product, regioselectively. DFT calculations (UM05/6-311++G(d,p)) were performed following the experimental studies in order to describe the outcomes correctly. Therefore, all possible reaction pathways were investigated for both diosphenol and tropolone. The reaction barriers and intrinsic barriers from the Marcus theory were calculated to investigate the thermodynamic and intrinsic electronic effects to the experimental product distribution. Both experiment and theory show that the aforementioned systems have different selectivity routes governed by several factors. As a result of this comparative study, the charge distribution at the reactive atoms, entropy factors for cyclization vs termination and aromatization of the ring effects were found to be the driving factors for the observed regioselectivity.

Original languageEnglish
Pages (from-to)1748-1755
Number of pages8
JournalChemistrySelect
Volume6
Issue number8
DOIs
Publication statusPublished - 24 Feb 2021

Bibliographical note

Publisher Copyright:
© 2021 Wiley-VCH GmbH

Funding

We gratefully acknowledge the computational source provided by the National High Performance Computing Center at Istanbul Technical University (Grant No: 5004722017); ITU BAP Project (Grant No. 39944) and project commission of Trakya University (TUBAP 2013/69) for financial support. The calculations reported in this paper were partially performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources). . We gratefully acknowledge the computational source provided by the National High Performance Computing Center at Istanbul Technical University (Grant No: 5004722017); ITU BAP Project (Grant No. 39944) and project commission of Trakya University (TUBAP 2013/69) for financial support. The calculations reported in this paper were partially performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources)

FundersFunder number
ITU BAP39944
National High Performance Computing Center
TUBITAK ULAKBIM
Trakya ÜniversitesiTUBAP 2013/69
Istanbul Teknik Üniversitesi5004722017

    Keywords

    • DFT
    • diosphenol
    • endo-exo selectivity
    • Marcus theory
    • radical cyclization
    • regioselectivity
    • tropolone

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