Yamamoto

Sekihara, K., H. Kohno, and S. Yamamoto, Theoretical prediction of x-ray CT image quality using contrast-detail diagrams. IEEE Transactions on Nuclear Science, 1982. NS-29(6) p. 2115-2121. 

The exact quantum expression for the activated rate constant was first derived by Yamamoto [6]. The resulting quantum reactive flux correlation fiinction expression is given by... 

Yamamoto T 1960 Quantum statistical mechanical theory of the rate of exchange chemical reactions in the gas phase J. Chem. Phys. 33 281... 

Jarvis S P, Yamada H, Yamamoto S-l, Tokumoto H and Pethica J B 1996 Direct mechanical measurement of interatomic potentials Nature 384 247... 

Akasaka T, Nagase S, Kobayashi K, Suzuki T, Kato K, Yamamoto K, Funasaka H and Takahashi T 1995 Exohedral derivatization of an endohedral metallofullerene Gd Cg2 J. Chem. See., Chem. Commun. 1343-4... 

Kolb D M, Kdtz R and Yamamoto K 1979 Copper monolayer formation on platinum single crystal surfaces Optical and... 

The regioselectivity benefits from the increased polarisation of the alkene moiety, reflected in the increased difference in the orbital coefficients on carbon 1 and 2. The increase in endo-exo selectivity is a result of an increased secondary orbital interaction that can be attributed to the increased orbital coefficient on the carbonyl carbon ". Also increased dipolar interactions, as a result of an increased polarisation, will contribute. Interestingly, Yamamoto has demonstrated that by usirg a very bulky catalyst the endo-pathway can be blocked and an excess of exo product can be obtained The increased di as tereo facial selectivity has been attributed to a more compact transition state for the catalysed reaction as a result of more efficient primary and secondary orbital interactions as well as conformational changes in the complexed dienophile" . Calculations show that, with the polarisation of the dienophile, the extent of asynchronicity in the activated complex increases . Some authors even report a zwitteriorric character of the activated complex of the Lewis-acid catalysed reaction " . Currently, Lewis-acid catalysis of Diels-Alder reactions is everyday practice in synthetic organic chemistry. 

The effect of ligands on the endo-exo selectivity of Lewis-acid catalysed Diels-Alder reactions has received little attention. Interestingly, Yamamoto et al." reported an aluminium catalyst that produces mainly exo Diels-Alder adduct. The endo-approach of the diene, which is normally preferred, is blocked by a bulky group in the ligand. 

A. Yamamoto, Organotransition Metal Chemistry, Academic Press, New York. 1986. 

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