A novel synthesis of (±)-mellein

Epr: The Indian Scene

“…4,4'-dimethoxyazobenzene, sym-trinitrobenzene and tetraphenylcyclopentanedienone (30). Simple Hiickel molecular orbital calculations suggest that the Li cation is rightly bound to one of the nitro groups of the sym-trinitrobenzene anion (30). McLachlan type calculations for tetracyclopentanedienone indicate the four phenyl rings are equally twisted (30°) with respect to the five-membered ring (30).…”

“…Other free radicals examined by us and others included heterocyclic semiquinones (29), radicals derived from tetraphenylhydrazine (10) and anions formed by alkali metal reduction of dicyclopropylketone. 4,4'-dimethoxyazobenzene, sym-trinitrobenzene and tetraphenylcyclopentanedienone (30). Simple Hiickel molecular orbital calculations suggest that the Li cation is rightly bound to one of the nitro groups of the sym-trinitrobenzene anion (30).…”

“…Simple Hiickel molecular orbital calculations suggest that the Li cation is rightly bound to one of the nitro groups of the sym-trinitrobenzene anion (30). McLachlan type calculations for tetracyclopentanedienone indicate the four phenyl rings are equally twisted (30°) with respect to the five-membered ring (30). Semiquinones in the solid state in hydroquinone and biphenyl matrices were shown to perform hindered rotation (31).…”

“…Anomalous line-width effects, arising from intermolecular and intramolecular exchanges, have been analyzed using the relaxation matrix theory developed by Freed and Fraenkel (35) in 2,2'-dinitrophenyl ether and sulphide radical anions, in 2,2'-dintrophenyl anion generated by alkali metal reduction and by electrolysis, and in the electrogenerated anions of o-, m-, p-nitrobenzonitrile and 1,8-dinitronaphthalene (30,36). Molecular orbital calculations were tested for their abilities to predict the electron spin densities of organic free radicals: alkyl, cyclohexadienyl and benzyl radicals, anions of cis and trans butadiene, trans stilbene, trans-l,2-bis(4-pyridyi)ethylene, cis and trans terephthaldehyde, benzaldehyde, acepleiadylene, acenaphth[l,2(a)]-acenaphthyene, nitro, cyano and amino benzenes, and nitrogen and sulphur containing heterocycles (30,37).…”

Synthesis of heterocycles via organopalladium intermediates

“…74) [154,155], isocoumarins (eq. 75) [156], anthraquinones [157], and phthalideisoquinolines [158], While these reactions are usually highly regioselective, they do not accommodate much functionality in the aromatic ring.…”