Regioselectivities in cyclizations of 4-substituted 4-penten-1-oxyl radicals have been investigated in a combined experimental and computational study (density functional theory). The progressive increase of the 6-endo-trig selectivity along the series of 4-substituents H < CH3 < C(CH3)(3) < C6H5 has been interpreted to originate from a balance between strain and FMO interactions. Torsional strain, which is associated with geometrical changes upon an approach of the reacting entities, is relevant for the 6-endo-trig but not for the 5-exo-trig reactions, as seen, for instance, in selective tetrahydrofuran formation from the 4-penten-1-oxyl radical and its 4-methyl derivative. The preference for tetrahydropyran formation in cyclizations of the 4-tert-butyl and the 4-phenyl-4-penten-1-oxyl radical has been attributed to FMO interactions between the terminal carbon atom of the pi bond and the O-radical center thus favoring the 6-endo-trig reaction on the basis of lower transition state energies.
Regiochemical control of intramolecular photochemical reactions of 1,6-heptadienes. Carbonyl-substituted 1-(4-alkenyl)-1-cyclopentenes
作者:Albert R. Matlin、Clifford F. George、Steven. Wolff、William C. Agosta
DOI:10.1021/ja00272a038
日期:1986.6
Mihailović, M. Lj; Gojković; Milosavljević, Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1999, vol. 38, # 1, p. 101 - 105
作者:Mihailović, M. Lj、Gojković、Milosavljević、Konstantinović
DOI:——
日期:——
MATLIN A. R.; GEORGE C. F.; WOLFF S.; AGOSTA W. C., J. AMER. CHEM. SOC., 108,(1986) N 12, 3385-3394
作者:MATLIN A. R.、 GEORGE C. F.、 WOLFF S.、 AGOSTA W. C.
DOI:——
日期:——
BECKWITH A. L. J.; MOAD G., AUSTRAL. J. CHEM., 1977, 30, NO 12, 2733-2739