Arene condensed

In nonaqueous solutions, two other types of reactions have been observed with polycyclic arenes condensation via free-radical reactions and oxidative ring fission. 

A series of seven p-t-butylcalixarenes (/>-t-butylcalix[n]arene where = 4-10) and bishomooxacalix[4]arene (condensation products of p-r-butylphenol and formaldehyde) were resolved on a Cig column (A = 288 nm) using a 15-min 90/10/0/0.1-> 40/0/60/0.1 acetonitrile/methanol/ethyl acetate/TFA gradient [912]. Peaks for 5 ppm standards were easily detected. 

The key initiation step in cationic polymerization of alkenes is the formation of a carbocationic intermediate, which can then interact with excess monomer to start propagation. We studied in some detail the initiation of cationic polymerization under superacidic, stable ion conditions. Carbocations also play a key role, as I found not only in the acid-catalyzed polymerization of alkenes but also in the polycondensation of arenes as well as in the ring opening polymerization of cyclic ethers, sulfides, and nitrogen compounds. Superacidic oxidative condensation of alkanes can even be achieved, including that of methane, as can the co-condensation of alkanes and alkenes. 

Fluoroalkjiations are frequentiy performed indirectly using tandem reactions. Arenes react with sodium borohydride in trifluoroacetic acid to afford otherwise difficult to obtain l,l,l-trifluoro-2,2-diarylethanes. Presumably sodium borohydride reacts initially with the trifluoroacetic acid to produce the trifluoroacetaldehyde or its equivalent, which rapidly undergoes Friedel-Crafts-type condensation to give an intermediate carbinol. The carbinol further alkylates ben2ene under the reaction conditions giving the observed product. The reaction with stericaHy crowded arenes such as mesitylene and durene... 

The condensation of an aldehyde with resorcinol gives rise to calix (3) arene (114). Isoprene reacts with resorcinol under acidic conditions to give ben2odipyran (24) and monochroman (25) (115). 

Notice that the horizontal bonds between carbons aren t shown in condensed structures—the CH3, CH2, ancl CH units are simply placed next to each other—but the vertical carbon-carbon bond in the first of the condensed structures drawn above is shown for clarity. Notice also in the second of the condensed structures that the two CH3 units attached to the CH carbon are grouped together as (0-13)2. 

Organic molecules are usually drawn using either condensed structures or skeletal structures. In condensed structures, carbon-carbon and carbon-hydrogen bonds aren t shown. In skeletal structures, only the bonds and not the atoms are shown. A carbon atom is assumed to be at the ends and at the junctions of lines (bonds), and the correct number of hydrogens is menially supplied. 

The 2-methyl group of 2-methyl-3T/-azepines, e.g. 11, is surprisingly reactive and undergoes rapid deuterium exchange and, in the presence of base, aldol condensation with areneal-dehydes to yield styryl derivatives, e.g. 12.76108... 

Table 2. 1,4-Diazocine Derivatives by the Condensation of 1,2-Dicarboxylic Acid Derivatives with Arene-1.2-diamines...

Co-condensation of Hf and Zr atoms from an electron-gun evaporation device, with P(Me)3 and arenes at 77K gave good yields of the species [M(arene)2P(Me3)]. Metal vapor synthesis led to Fe(i7 -arene)L2 and Fe(i7 -arene)-(i7 -diene), where L is a phosphorus ligand. In addition, complexes of stoichiometry Fe(T) -diene)L3 (where L is again a... 

Benzene and naphthalene compounds can be formylated under Vil-smeir conditions. The formyl compounds, with or without isolating, can be condensed with amino arenes to give leuco compounds. In this reaction, the benzhydrol intermediate is not isolated.21,79,84 86 The reaction is generally carried out in an alcohol solvent such as isopropanol, butanol, or pentanol and an acid catalyst such as hydrochloric acid, sulfuric acid, or methanesul-fonic acid.87 Acetic acid can also be used both as catalyst and as the solvent. Urea sometimes is added as catalyst.84,88 Terephthaldehyde reacts with W-diethyl-3-methylaniline89 and substituted azulenes to give a bis-triphenylmethane21 57 and 58, respectively. 

Co-condensation of transition metal atoms with arenes such as benzene and toluene is well known to yield bis-arene-metal compounds. However, in many cases the yields based on the metal atoms are less than 40%. Evidence that competing reactions such as carbon-hydrogen activation can occur is provided by the isolation of non-metal-containing products such as biaryl derivatives (2JL). ... 

Reaction of rhenium atoms with alkyl-substituted arenes forms dirhenium- l-arylidene compounds (2 2) (Figure 3). The products require insertion, presumably sequential, into two carbon-hydrogen bonds of the alkyl substituent. These reactions seem highly specific and require only the presence of an alkyl-substituted benzene that possesses a CH2 or CH3 substituent. Thus, co-condensation of rhenium atoms with ethylbenzene gives two isomers (see Figure 3) in which the products arise from insertion into the carbon-hydrogen bonds of the methylene or the methyl group. The product distribution in this reaction is in accord with statistical attack at all available sp3 C-H bonds. 

An orthometallation procedure for the preparation of condensed iso-thiazolium salts from appropriately substituted arenes has been described earlier in this Section (Scheme 117)180 an example illustrating the way in which this approach can be elaborated to the synthesis of condensed 1,2-dithiolylium perchlorates is given in Scheme 123. 

A,A -di(/>-dimethylamino-benzyl) derivatives of di(imidazolidinylidene)gold(i) salts were polymerized into polyimides by condensation with arene-tetracarboxylic anhydrides. The products are tough, but flexible, and have high glass transition temperatures and high thermal stability. Yellow films of the materials are transparent above 365 nm.279... 

There is no experimental evidence for 7r-complexation of arenes to gold centers in the condensed phase. Quantum-chemical calculations were carried out on various levels of theory for 1 1 and 2 1 complexes of benzene and substituted benzenes with Au+ in the gas phase. For all model systems investigated, it has been predicted that an -coordination to a single carbon atom is the ground state of the cation (Cy-symmetry for [(C6H6)Au]+ and 6 -symmetry for [(C6H6)2Au] ). Similar results were obtained for hexafluorobenzene, for which a coordina-... 

Condensation of aryl halides with various active methylene compounds is readily promoted by catalytic action of palladium to give the corresponding arene derivatives containing a functionalized ethyl group [7]. Yamanaka et al. extended this chemistry to haloazoles including oxazoles, thiazoles and imidazoles [8]. Thus, in the presence of Pd(Ph3P)4,2-chlorooxazole was refluxed with phenylsulfonylacetonitrile and NaH to form 4,5-diphenyl-a-phenylsulfonyl-2-oxazoloacetonitrile, which existed predominantly as its enamine tautomer. In a similar fashion, 4-bromooxazole and 5-bromooxazole also were condensed with phenylsulfonylacetonitrile under the same conditions. 

We have found several examples in which adjacent cationic charge centers are shown to activate carboxonium electrophiles. A convenient method for studying this activation is through the use of the hydroxyalkylation reaction, a commercially important, acid-catalyzed condensation of aldehydes and ketones with arenes.10 It is used for example in the synthesis of bis-phenol A from acetone and phenol (eq 6). While protonated acetone is able to react with activated arenes like phenol, it is not capable of reacting with less nucleophilic... 

The hydrogenolysis of the condensates over a C0O-M0O3-AI2O3 catalyst takes place quantitatively under mild reaction conditions, and a tetramethylbenzene mixture with the following composition is obtained with 92-95% selectivity to Cjo arenes ... 

Thirty-five different asym DAMs were synthesized by the condensation reaction of benzyl alcohols and arenes in the presence of an acid catalyst. 

Ordinarily, p-toluenesulfonic acid has been used as the catalyst. Although p-toluenesulfonic acid has high activity, its use results in the formation of by-products such as methylbenzyl-p-toluenesulfonates, high molecular weight condensates, and esters. We found that formic acid is a better catalyst for this reaction and gives almost quantitatively the mixture of HexMeDPM in a pure state without any contamination due to undesirable by-products. Formic acid also serves as a solvent. From this study, it was found that benzyl alcohols react easily with arenes to form asym DAMs, and formic acid is the most favorable catalyst for the benzylation reaction. 

A series of asym DAMs were synthesized by the condensation reaction of arenes with benzyl alcohols. Benzene, p-xylene, mesitylene, durene, and isodurene were used as arenes because they give only one condensation product. For example, pure 2,5,3 -TrMeDPM is easily prepared by a distillation of the crude product obtained by the following reaction ... 

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