Highly Substituted Naphthalenes

Naphthalenes with eight substituents usually show twisted structures. The twist can be attributed to nonbonded steric interactions between substituents on Cl and C8 and on C4 and C5. The distance between Cl and C8 in naphthalene is only 2.5 A, which is invariably shorter than the sum of the van der Waals radii of the two 

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Additional bands may appear because of ring bending vibrations. The position of absorption bands for more highly substituted naphthalenes and other polynuclear aromatics are summarized by Colthup et al. (1990) and by Conley (1972). 

In the spectra of a-substituted naphthalenes, the bands for the isolated hydrogen and the two adjacent hydrogen atoms of /3-naphthalenes are replaced by a band for three adjacent hydrogen atoms. This band is near 810-785 cm 1. Additional bands may appear because of ring bending vibrations (see Table 2.3). The position of absorption bands for more highly substituted naphthalenes and other polynuclear aromatics are summarized by Colthup et al. (1990) and by Conley (1972). 

The reaction of a cyclic zirconium-diene complex and an aryl diiodide, with CuCl, leads to highly substituted naphthalene derivatives. ... 

Two isomeric monosubstituted naphthalenes are differentiated by the prefixes 1- and 2-, or a- and 3 For more highly substituted naphthalenes, the arrangement of the substituents is indicated by numbers. Since there are three substituent groups on the naphthalene ring of cadalene, we must use the number system ... 

Highly substituted naphthalenes, such as octamefhylnaphthalene (4), also exhibit significant twists of the aromatic system [11, 12], The X-ray structure of decaphenylanthracene (5) shows a large end-to-end twist [13]. Higher acenes with overcrowded structures, such as octaphenyldibenzo[a,c]naphthacene 6 [14], have also been reported to show high degrees of twist. 

Condensation between A-dimethylaminopyrrole (102) and tetramethylbenzyne (103), generated in situ from l,2-dibromo-3,4,5,6-tetramethylbenzene, to form the cycloadduct 104 followed by pyrolysis to form 4 (Scheme 22) [11] represents a general pathway for highly substituted naphthalenes. 

Condensation between tetraphenylcyclopentadienone (105) and tetraphe-nylbenzyne (106), generated in situ by diazotization of tetraphenylanthranilic acid, to form 107 followed by decarbonylation to form 100c (Scheme 23) [13] represents an alternative general pathway for highly substituted naphthalenes. 

Wu Y-T, Huang K-H, Shin C-C, Wu T-C (2008) Palladium-catalyzed formation of highly substituted naphthalenes from arene and alkyne hydrocarbons. Chem-Eur J 14 6697-6703. doi 10.1002/aSSN)1521 -3765... 

Fukutani T, Hirano K, Satoh T, Miura M (2009) Synthesis of highly substituted naphthalene and anthracene derivatives by rhodium-catalyzed oxidative coupling of arylboronic acids with alkynes. Org Lett 11 5198-5201. doi 10.1021/ol9021172... 

Addition of internal alkynes to allylarenes (86), catalysed by the (AcO)2Pd/( AcO)2Cu system with O2 as the terminal oxidant, has provided a new route to highly substituted naphthalenes (87). The reaction proceeds via ar-coordination of an allylic C=C bond to Pd(II), followed by ortho-C-H activation... 

Interestingly, the presence of the acceptor PF3 ligands in [Cr( /6-naphthalene)(PF3)3] makes the coordinated naphthalene become activated toward attack by nucleophiles. Thus treatment with stabilized carbanions and either I2 or Ce(IV) salts affords high yields of the a-substituted naphthalenes (102) (Scheme 7). 

The bioaccumulation potentials of the major components of gasoline range from low to high. Some higher molecular weight components (e.g., naphthalene and substituted naphthalenes) may be taken up by fish and domestic animals and bioconcentrated if they persist in environmental media (Air Force 1989). Alkenes have low log octanol/water partition coefficients (K°w) of about 1 and estimated bioconcentration factors (BCF) of about 10 aromatics have intermediate values (log K° values of 2-3 and BCF values of 20- 200), while O and greater alkanes have fairly high values (log K°w values of about 3-4.5 and BCF values of 100-1,500) (NESCAUM 1989). 

Treatment of 1-substituted naphthalenes with butyllithium in a number of cases leads to exclusive introduction of lithium into the 2-position. There are only a few types of substituents that direct the metallation mainly towards the 8-position. The observed regio-preferences have not yet been explained in a satisfactory way. When a mixture of 1-naphthyllithium and BuLi TMEDA is heated under reflux for 3 hours, 1,8-dilithionaphthalene is formed as the exclusive product in a high yield. The metallation of the 8-position presumably takes place in the 1 1 aggregate of 1-naphthyllithium and BuLi. 

High yield and selective formation of carbonyl compounds from aromatic olefins have been obtained in air-saturated acetonitrile solution [Eq.(16)] [123-125]. The combination of a radical cation of the alkene and an oxygen radical anion gives a dioxane intermediate which then undergoes cleavage. For substituted naphthalenes, the oxidative cleavage can be stopped at the side chain of one benzene ring [Eq. (17)] [126]. 

Von Schiitz and Wolf [29] have likewise investigated a second typical stochastic reorientation motion using NMR in molecular crystals the hindered rotation of methyl (CH3 -) groups in ten different methyl-substituted naphthalene crystals. The reorientation motions are, at not-too-low temperatures, the dominant source of nuclear spin-lathce relaxation in these highly purified molecular crystals. Only at very low temperatures do thermally-activated reorientation processes cease to play a role. The spin-lattice relaxation is then determined essentially by paramagnetic impurities. 

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