Mechanism of the forbidden [3s,5s]-sigmatropic shift: orbital symmetry influences stepwise mechanisms involving diradical intermediates

Chemistry : a European Journal
Andrew G LeachK N Houk

Abstract

The mechanisms of [3s,5s]-sigmatropic shifts of octa-1,3,7-triene and 7-methylenenona-1,3,8-triene have been elaborated using B3LYP and BPW91 density functional theory and CASPT2 methods. These orbital symmetry forbidden rearrangements are stepwise, involving diradical intermediates. A comparison with several [3,3]-sigmatropic shifts of substituted hexadienes and of [5,5]-sigmatropic shifts that are allowed, but nevertheless follow stepwise paths, shows that the activation barrier for the disallowed [3,5] shift is significantly larger than that for the stepwise reactions that are orbital symmetry allowed. Cyclic diradicals that have an aromatic circuit of electrons including the two radical centers and conjugated pi or sigma bonds are stabilized as compared to cyclic diradicals with an antiaromatic circuit of electrons. This applies to the transition states leading to and from the diradicals and influences the activation energies of stepwise sigmatropic shifts. The magnitudes of these effects are small but will have a significant influence on the rates of competing processes. This series of calculations has been used to assess the relative capabilities of the two functionals. We find that BPW91 underestimates the endothermicity...Continue Reading

References

Dec 26, 2001·Chemical Reviews·P R Schleyer
Feb 6, 1970·Science·R Hoffmann, R B Woodward
Jul 3, 1996·Journal of the American Chemical Society·Paul von Ragué SchleyerNicolaas J R van Eikema Hommes

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Citations

May 20, 2015·Journal of Molecular Modeling·Nasir KhanKhurshid Ayub
May 27, 2016·The Journal of Organic Chemistry·Q Nhu N Nguyen, Dean J Tantillo
Oct 2, 2014·Natural Product Reports·Martin E Tanner
Jul 29, 2016·Organic & Biomolecular Chemistry·Ghislain Deslongchamps, Pierre Deslongchamps
Sep 10, 2013·Chembiochem : a European Journal of Chemical Biology·Niusha Mahmoodi, Martin E Tanner
Dec 21, 2012·Chemical Communications : Chem Comm·Isaac J SugdenRobert G Bell
Jul 18, 2012·Physical Chemistry Chemical Physics : PCCP·Jason G Harrison, Dean J Tantillo
Jul 28, 2012·Chemistry : a European Journal·Osvaldo GutierrezDean J Tantillo
Nov 16, 2017·Organic & Biomolecular Chemistry·Trideep RajaleDavid M Birney
Jan 27, 2005·Journal of the American Chemical Society·Kelli S KhuongK N Houk
Jan 24, 2015·The Journal of Organic Chemistry·Hannelore GoossensSaron Catak
May 19, 2012·Journal of the American Chemical Society·Kerry GilmoreIgor V Alabugin
Dec 12, 2002·Journal of the American Chemical Society·Andrew G Leach, K N Houk

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