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Understanding anionic Chugaev elimination in pericyclic tetracene formation

Burroughs, Laurence; Ritchie, John; Woodward, Simon

Authors

Laurence Burroughs

John Ritchie

Simon Woodward simon.woodward@nottingham.ac.uk



Abstract

The reaction pathway for the formation of tetracenes from the diols 1,2-C6H4(CHOHC≡CAr)2 , LiHDMS, CS2 and MeI has been modelled by computational methods at the CBS-QB3 level of theory. Comparison of PhCHOC(=S)YCCPh (Y = S- or SMe) indicates a slight kinetic advantage for the anionic system towards [3,3]-sigmatropic rearrangement [Eact(calc.) 19.7 vs 21.8 kcal mol-1]. Using anthracene-based models, 10-{SC(=O)Y}-4a,10-dihydroanthracene (Y = S- or SMe), allows direct comparison of both syn and anti-manifolds in the neutral vs. anionic Chugaev elimination. Syn elimination of [HSC(=O)S]- is distinctly favoured [Eact(calc.) 11.4 kcal mol-1] vs. syn elimination of neutral methylated HSC(=O)SMe [Eact(calc.) 27.5 kcal mol-1]. The smaller barrier to syn elimination of the anionic leaving group is in accord with the low temperature conditions required for this Chugaev reaction (60 oC) and suggests a general advantage in carrying out Chugaev eliminations in anionic manifolds.

Journal Article Type Article
Publication Date Mar 31, 2016
Journal Tetrahedron
Print ISSN 0040-4020
Electronic ISSN 0040-4020
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 72
Issue 13
APA6 Citation Burroughs, L., Ritchie, J., & Woodward, S. (2016). Understanding anionic Chugaev elimination in pericyclic tetracene formation. Tetrahedron, 72(13), doi:10.1016/j.tet.2016.02.025
DOI https://doi.org/10.1016/j.tet.2016.02.025
Publisher URL http://www.sciencedirect.com/science/article/pii/S0040402016300886
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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