Indoloindolizinas: La historia completa de un andamio aromático policíclico desde el diseño teórico hasta las aplicaciones de transistores de efecto de campo orgánico
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Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom,...
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
Dienophiles with one or more electron-withdrawing substituents form stereochemically different products in which the substituents are oriented in an endo (towards) or exo (away) configuration relative to the double bond.
The endo isomer is formed faster and is the kinetic product. The exo isomer is more stable and is the thermodynamic...