Aromatic compounds, fused methyl

The latter reagent also methylates certain heterocyclic compounds (e.g., quinoline) and certain fused aromatic compounds (e.g., anthracene, phenanthrene). The reactions with the sulfur carbanions are especially useful, since none of these substrates can be methylated by the Friedel-Crafts procedure (11-12). It has been reported that aromatic nitro compounds can also be alkylated, not only with methyl but with other alkyl and substituted alkyl groups as well, in ortho and para positions, by treatment with an alkyllithium compound (or, with lower yields, a Grignard reagent), followed by an oxidizing agent such as Bra or DDQ (P- 1511). 

This reaction is most often carried out with R = aryl, so the net result is the same as in 14-17, though the reagent is different. It is used less often than 14-17, but the scope is similar. When R = alkyl, the scope is more limited. Only certain aromatic compounds, particularly benzene rings with two or more nitro groups, and fused ring systems, can be alkylated by this procedure. 1,4-Quinones can be alkylated with diacyl peroxides or with lead tetraacetate (methylation occurs with this reagent). 

This procedure illustrates formylation by N,N-dimethylamino-methoxymethylium methyl sulfate, a compound which can be produced readily by reaction of easily available materials. 6-(Dimethylamino)fulvene is a useful intermediate for the synthesis of various fused-ring nonbenzenoid aromatic compounds. 

The infrared spectra of some other types of highly chlorinated aromatic compounds (a//-quasiperchloro compounds, perchloro-di- and triphenyl-methyl radicals, fused polycyclic aromatic chlorocarbons, aromatic chloro-carbon ions) have also been recorded and reviewed (Ballester et al., 1978c). 

The it energy of a non-classical conjugated hydrocarbon can be compared directly with that of a classical analogue by the PMO method.14 Consider an even monocyclic polyene. This can be formed by fusion of methyl with an odd AH with one atom less. These components can also be fused to form an acyclic polyene. Comparison gives the aromatic energy of the cyclic system by difference. In this way we find that rings with An + 2 atoms are more stable, and those with An atoms less stable, than analogous acyclic compounds. The same method can be used for the bicyclic systems XVII, XIX, XXI, XXII, XXIII. The procedure is indicated below... 

Stability differences between cis and trans cyclopentane-fused 1,3-oxazines were also observed in the case of the ring-chain tautomeric mixtures 119-121, obtained by reacting cis- and trans-2-hydroxymethylcyclopentylamine with aromatic aldehydes [149]. The ring form of the trans derivatives is present in fairly low amount as compared with the cis compounds [149, 150]. jV-Methyl substitution stabilizes the ring forms in both the cis and trans cases [149]. For a detailed discussion of the ring-chain tautomerism of alicyclic 1,3-amino alcohols, see, for example, refs. [150, 151]. 

The TT-cyclization of A/ -acyliminium ions onto aromatic rings is a useful method for the preparation of isoquinolines fused with heterocycles. Heating azide 102 with one of the compounds methyl (5)-mandelate (103) or methyl (i )-mandelate (63) in toluene provides the carbamates 104 and 105 respectively. DIBAL reduction of 104 or 105 with DIBAL in toluene... 

Intramolecular condensation reactions of activated thiol compounds (e.g., a-thioglycolate derivatives) have been utilized to prepare fused thiophene compounds. For example, treatment of imine 5 with methyl thioglycolate gave the nucleophilic aromatic substitution... 

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