Synthetic methods of aromatic compounds from aliphatic compounds can be classified as follows :
(A) Cyclohexene derivatives, obtained by Friedel-Crafts heaction from diene and dienophile are dehydrogenated to aromatic compounds.
(B) Cyclotrimerization of acetylenic compounds.
(C) Inter-and intra-molecular condensation of appropariate dicarbonyl-compounds and then the dehydrogenation of thus obtained cyclohexenone derivatives to the aromatic compounds.
(D) Another various methods.
This article concerns exclusively to the (C) method. The (C) method can be further divided into the following three sub-methods :
C-1. Michael addition of active methylene and active methyl compounds to α, β-unsaturated carbonyl- compounds and then the adducts,
i.
e. the δ-dicarbonyl-compounds are cyclized intramolecularly to the cyclohexenone derivatives. The cyclization reactions are aldol-or ester condensation and thus obtained cyclohexenone derivatives are dehydrogenated to the corresponding aromatic compounds.
C-2. Two molecules of active methylene compounds are joined by aldehydes (formaldehyde or acetaldehyde) or formic acid and thus obtained δ-dicarbonyl-compounds are then cyclized intramolecularly as in the case of C-1.
C-3. Two molecules of dicarbonyl-compounds are intermolecularly cyclo-condensed directly to the substituted benzene-derivatives or at first to the cyclohexane-dione compounds and then dehydrogenated to the aromatic compounds.
Many examples, according to the above-mentioned classifications, are given in this article.
抄録全体を表示