Naphthalene derivatives 1,8-disubstituted

The number of naphthalene derivatives is very large, since the number of positional isomers is large 2 for monosubstitution, 10 for disubstitution—same substituent, 14 for disubstitition—different substituents, 14 for trisubstitution—same substituent, 42 for trisubstitution—two different substituents, 84 for trisubstitution—three different substituents, and so on with multiplying complexity. 

Much the same confusing situation applies to the energetics of 1,2- and 1,4-disubstituted naphthalene derivatives. That the 1,4-species is meaningfully more stable than either of its... 

The construction of peri-annelated heterocyclic systems I-XXIII is carried out by the addition of a three carbon-atom fragment to the ben-zoheterocycle (3 — 2) or of a heterocycle to a naphthalene nucleus (4 — 2) (see Scheme 1). In practice, the second approach (4 — 2) is used more often. 1,8-Disubstituted naphthalene derivatives serve as the initial compounds, and they may be divided into three main types (5-7) as potential precursors of peri-heterocycles I-XXIII (Scheme 2). 

The reactivity, site of attack, and stereochemistry of the reactions of a variety of nucleophiles (oxygen, sulfur, nitrogen, organometallic) with anti-and syn-naphthalene 1,2 3,4-dioxides have been studied recently.159 In most cases, di- or tetrasubstituted tetrahydronaphthalene products arising from attack at C-l and C-4 positions in the anti mode are produced. These isomeric diepoxides are excellent intermediates for the preparation of a number of difficulty accessible 1,4-disubstituted naphthalene derivatives. 

The C-N bond cleavage of a benzo tetrahydroisoquinoline compound with lithium metal followed by aqueous quenching formed a naphthalene derivative Equation (1) <2000T8375>. An isoquinolinium ring system has been converted into a highly functionalized 1,2-disubstituted benzene compound. Ring opening of the quaternary salt was... 

An example that illustrates both of the above parameters is shown in Fig. 38. Not only is the emission from the 2,7-disubstituted naphthalene derivative... 

Dioxetanes are beginning to have a tremendous impact on chemiluminescent methodologies for clinically relevant analytes. This impact is due to the development of dioxetanes as enzyme substrates in enzyme-amplified assays similar to the type described in Section 1.3.2. The evolution of the current generation of highly efficient substrates merits some comment. Schaap and co-workers (S8) showed that the naphthalene silyl ether shown in Fig. 40a could be triggered by fluoride ions to give chemiluminescence with a quantum yield of 0.01. On the other hand, the /nefa-disubstituted phenyl derivative in Fig. 40b is extremely efficient in a CIEEL chemiluminescence process (for reasons outlined in the previous section) with a quantum efficiency of 0.45. Subsequent studies showed that the naphthalene derivative in Fig. 40a with an 0-acetyl group instead of the silyl ether, could... 

Shirley and Cheng (20) reported in 1969 that metalation of 1-meth-oxynaphthalene by BuLi produces a mixture of the 2-lithio and the 8-lithio derivatives in an overall yield of 28% as shown by carbonation. When the same reaction conditions are used except that one equivalent of TMEDA is added, a shift in product composition to > 99.3% 2-metala-tion and < 0.3% 8-metalation occurs, and the yield of l-methoxy-2-naphthalenecarboxylic acid increases to 60%. On the other hand, metalation of 1-methoxynaphthalene with tert-BuLi in pentane-cyclohexane solvent gives a product representing 97% 8-metalation and 3% 2-metala-tion. These selective metalations therefore constitute a useful synthetic route to 1,2- and 1,8-disubstituted naphthalene derivatives. 

The degree of pyramidalization at the N atom of these compounds permits to distinguish between covalent bond type attraction and other attractive forces. For example, in strained 1,8-disubstituted naphthalene derivatives the distance between pen -substituents is always intermediate between the sum of the covalent radii and the sum of vdW radii if the substituents are potentially a donor and an acceptor (e.g. N or P vs Si), this may be interpreted as a DA bonding. However, Schiemenz et al. [154-156] have shown that the proximity between these substituents is due only to the rigidity of the naphthalene skeleton, indeed, the observed inter-substituent distances substantially longer than 2.50-2.60 A are evidence/or steric repulsion and against DA interactions. 

The nucleophilic catalysis of amide isomerization, whereby the formation of a tetrahedral intermediate disrupts amide resonance and facilitates rotation about the C—N bond (Scheme 10), has hitherto remained uncharacterized. Now, two types have been demonstrated, each of them 1,8-disubstituted naphthalene derivatives. In the first. 

Several of these // -disubstituted [ C]formamides have demonstrated utility in C-[ " C]formylations of electron-rich aromatic and heteroaromatic substrates via the Vilsmeyer-Haack reaction °. In the presence of POCI3, Cl2(0)P0P(0)Cl2, (COCl)2 or (CF3S02)20 they can C-formylate benzene and naphthalene derivatives that possess an electron-releasing substituent (0-alkyl, S-alkyl, A -dialkyl) as well as anthracene, pyrrole. 

The benzo-annellated derivative naphtho[l,2-c]furoxan is numbered according to the system (2)] shown. In the literature the name 1,2-naphthofuroxan may often be found, with the same numbering as for a 1,2-disubstituted naphthalene. Although the latter method is perhaps a little clearer to follow, the more systematic scheme (2) will be adhered to in this chapter. 

Diazomethyl)-1,4-diphenyl-1,2,3-triazole (354) reacts with 1,4-disubstituted benzenes or naphthalenes to give a mixture of carbene derived norcaradiene/cycloheptatriene products (355) and (356) (Scheme 68). Attack is favored adjacent to the more highly branched substituent. When R = = Pr, a mixture of triazole derivatives (357) and (358), formed by addition to benzene and... 

Cotton effects of skewed biaryls with restricted rotation around the formal single C—C bond can be analyzed in the exciton approximation, provided that the polarization direction of the transition is well defined71 78 (Section4.4.2.2.). Typical examples are derivatives of 2,2 -disubstituted 1,1 -binaphthyl 3 having a dihedral angle between the two naphthalene rings of 65-95°79. 

Selective mono- or dicyclohexylation of naphthalene with cyclohexene (and cyclohexyl bromide) was achieved over HY zeolites.170 Monocyclohexylnaphtha-lenes are formed with 99% selectivity at 80°C. The amount of dicyclohexyl-naphthalenes increases dramatically with increasing temperature. Due to zeolite shape selectivity, mainly the p,p-disubstituted derivatives (2,6- and 2,7-dicyclo-hexylnaphthalene) are formed at 200° C. 

Carbon-13 shifts of multisubstituted naphthalenes can be assigned by addition of substituent increments similar to eq. (4.16), provided no intramolecular interactions between substituents take place. This applies for 1,4-, 1,5-, 2,6-, and 2,7-disubstituted deriv-... 

An application of the nickel catalysis is shown here in the formation of 2,7-disubstituted derivatives of naphthalene, which are less common in the library of commercial fine chemicals. For these reasons, the submitters developed some synthetic routes to 2,7-bis(diethylcarbamoyloxy)naphthalene, 2,7-dimethylnaphthalene4 and 2,7bis(bromomethyl)naphthalene that will facilitate access to a large family of 2,7-disubstituted naphthalenes.5 The low cost of N,N-diethylcarbamoyl chloride, relative to triflic anhydride (for making aryl triflates), allows... 

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