Trisubstituted aromatic compound

Pyridazines 160 were obtained by microwave-assisted reaction of 1,4-dicarbonyl compounds and hydrazine in AcOH and in the presence of DDQ as oxidant in order to obtain the aromatic compound in a one pot reaction [ 105]. The yields reported were relatively low although the method can be applied to the preparation of arrays of trisubstituted pyridazines with high molecular diversity (Scheme 57). 

The acid-catalyzed dimerization of pyrroles and indoles also involves electrophilic attack by the 2H- or 3//-protonated species upon the non-protonated heterocycles (Schemes 6, 7 and 8, Section 3.05.1.2.2), and 3,3-dimethyl-3//-indole has been reported to react with 7r-electron-rich aromatic compounds to yield the 2-ary.l-3,3-dimethyl-2,3-dihydroindoles (77S343). In the absence of a nucleophile strong acids promote the interchange of substituents at the 2- and 3-positions of 2,3,3-trisubstituted 3//-indoles, e.g. (510) (511) (62JOC1553). 

The photostimulated reaction of o-, m-, and p-C6H4Cl2 with Mc3Sn ions gives disubstitution in 58%, 90%, and 88% yield, respectively [39] in addition, methyl 2,5-dichlorobenzoate and methyl 3,6-dichloro-2-methoxybenzoate afford bistannylated aromatic compounds in 99% and 64% yields, respectively [40]. Disubstitution products are also obtained by the reaction of 2,6-and 3,5-dichloropyridine under photoinitiation in about 80% yield (Scheme 10.26). Even trisubstitution is possible by the photoinduced reaction of 1,3,5-C6H3C13 with Me3Sn ions in liquid ammonia, in 71% yield [39]. 

The carboxyl-based TL 1.43 (101) was easily prepared from hydroxymethyl PS resin and a trisubstituted aromatic compound its SP fimctionahzation on the amide carbonyl or on the chlorine atom is followed by cleavage with TMSl (trimethyl silyl iodide) for 72 h at 75 °C to obtain simultaneously ester hydrolysis and decarboxylation to 2-unsubstituted quinazolines. An expansion to other heterocyclic systems is easily foreseeable. 

Oxidation of Aromatic Compounds Reduction of Aromatic Compounds Synthesis of Trisubstituted Benzenes... 

We see what interest is attached to the study of active aromatic compounds, and how necessary it is that chemists who are dealing with bi- and trisubstitution products of benzene capable of being active should attempt the separation of their dextro- and laevorota-tory isomers. We shall proceed to show that bodies obtained by synthesis consist, in fact, of equal proportions of these isomers. 

Olefins react extremely rapidly with HO, with most rate constants within an order of magnitude of the diffusion-controlled limit (Atkinson, 1986). Probably the most reactive hydrocarbon yet tested is the monoterpene myrcene (18), with two vinyl groups and a trisubstituted double bond. It reacts with OH about three times as fast as isoprene and about thirty times as fast as ethylene (Altshuller, 1983). Aromatic compounds usually react somewhat faster than alkanes and somewhat slower than alkenes. 

The co-operative effect of 1,3-interrelated directing groups is a powerful strategy in synthesis. This allows the otherwise difficult preparation of 1,2,3-trisubstituted aromatic compounds. Hence the lithiation of the aromatic compound 129 is directed by both the methoxy and secondary amide groups (1.118). Two equivalents of the... 

There are many reasons why scientists want to measure the Raman spectra of compounds. First, many bands that are weak in the infrared spectrum are among the strongest bands in the Raman spectrum. For example, the S—S and C=C stretching bands are often so weak as to be essentially unrecognizable in the IR spectrum but stick out like the proverbial sore thumb in a Raman spectmm. Second, some Raman bands are found at very characteristic frequencies. For instance, monosubstituted aromatic compounds, together with 1,3-disubstituted and 1,3,5-trisubstituted aromatics, have a very intense band at 1000 cm. This band, along with the presence or absence... 

For monosubstituted aromatic compounds such as toluene (methylbenzene), there is an absorption at 730 cm for the out-of-plane bending of five adjacent hydrogen atoms. There is another absorption in the 745—690 cm region that characterizes monosubstituted, 1,3-disubstituted, and 1,2,3-trisubstituted aromatic compounds (Figure 2.19). 

To obtain the lUPAC name of a trisubstituted aromatic compound, we number the benzene ring to give the lowest possible numbers to the carbon atoms bearing the substituents. Thus, each substituent has both a name and a number. 

At the trimer diradical (tn) step, two reaction pathways are again possible termination by cyclization-aromatization giving trisubstituted benzene sf ies or propagation by addition to a monomer molecule to give tetramer diradicals In (scheme 3). TTie cyclization process will give directly the three aromatic trimers fi-JQ observed experimentally. This is an important point, because monoradical mechanism (27, 28) could not afford the formation of the 1,2,3-trisubstituted isomer type, such as compound Q. 

By incorporating trisubstituted aromatic rings, Vogtle has prepared what he calls endo-lipophilic cryptands . Such a compound is illustrated below as 8. The synthetic approach to these systems parallels those outlined in previous discussion . 

Both aliphatic and aromatic terminal alkynes reacted with aliphatic aldehydes giving exclusively a mixture of ( ,Z)-1,5-dihalo-1,4-dienes and disubstituted ( )-a,p-unsaturated ketones, the former being the major products in all cases. When nonterminal aromatic acetylenes were used, the trisubstituted ( )-a,p-unsat-urated ketones were the exclusive compounds obtained. The procedure was not valid for ahphatic and unsaturated alkymes. However, the catalytic system was found to be compatible with alcohols and their corresponding acetates although limited yields were obtained. 

The 3-oxo-2-pyrazolidinium ylides 315, easily available by reaction of the corresponding pyrazolidin-3-one with aromatic aldehydes, function as 1,3-dipoles in cycloaddition reactions with suitable alkenes and alkynes to provide the corresponding products. When unsymmetrical alkynes are used, mixtures of both possible products 316 and 317 are usually obtained (Equation 45). The regioselectivity of cycloadditions of the reaction with methyl propiolate is influenced by the substituents on the aryl residue using several 2,6-di- and 2,4,6-trisubstituted phenyl derivatives only compound 316 is formed <2001HCA146>. Analogous reactions of 3-thioxo-l,2-pyrazolidinium ylides have also been described <1994H(38)2171>. 

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