Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/141244
Title: How an early or late transition state impacts the stereoselectivity of tetrahydropyran formation by intramolecular oxa-Michael addition
Authors: Csókás, Dániel
Ho, Annabel Xuan Ying
Ramabhadran, Raghunath O.
Bates, Roderick Wayland
Keywords: Science::Chemistry
Issue Date: 2019
Source: Csókás, D., Ho, A. X. Y., Ramabhadran, R. O., & Bates, R. W. (2019). How an early or late transition state impacts the stereoselectivity of tetrahydropyran formation by intramolecular oxa-Michael addition. Organic & Biomolecular Chemistry, 17(25), 6293-6304. doi:10.1039/C9OB00750D
Journal: Organic & Biomolecular Chemistry
Abstract: The intramolecular oxa-Michael addition giving tetrahydropyrans has been examined experimentally using both acidic and basic catalysis. With acidic catalysis, the diequatorial product is exclusively obtained in a kinetically controlled reaction in all cases. Under basic conditions at low temperature, the reaction is again under kinetic control, but formation of the axial-equatorial isomer is generally favoured with an (E)-Michael acceptor, although isomerisation to the diequatorial isomer is observed at higher temperatures. Computationally, it is found that the acid catalysed reaction has a late transition state and the kinetic favouring of the diequatorial isomer has a steric explanation. In contrast, under strongly basic conditions, an early transition state is found. Electrostatic effects are likely to be the main contributor to the stereoselectivity for the (E)-isomer and steric interactions for the (Z)-isomer.
URI: https://hdl.handle.net/10356/141244
ISSN: 1477-0520
DOI: 10.1039/C9OB00750D
Rights: © 2019 The Royal Society of Chemistry. All rights reserved. This paper was published in Organic & Biomolecular Chemistry and is made available with permission of The Royal Society of Chemistry.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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