Naphthalenes 1,3-disubstituted

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. 

A similar reaction was described by Nakamura et al. as recently as 2009. Here again, silver salts were not the best catalysts. Nevertheless, silver triflate was able to rearrange 2-alkynyl tetralones to 1,2-disubstituted naphthalenes (Scheme 3.55).83... 

Other nucleophile-electrophile pairs for which the pm-disubstituted naphthalene system has been used to monitor potential bonding interactions are illustrated in [35] and [36], The methoxynitrile [35], for example, shows the same sort of evidence for a bonding interaction, marked by a 7° distortion from linearity at the nitrile carbon, in plane, and exactly away from the methoxyl oxygen (Procter et al., 1981) so also does the bipyridyl dinitrile [37] (Baxter et al., 1991). In the unique case of the 8-diazonium quinoline-N-oxide [36] the proximity of a formally negatively charged oxygen induces a distortion from linearity of 10.4° in the diazonium group (Wallis and Dunitz, 1984). 

Table IV, which presents data (84T1667 88JOC2942) on the ring-chain equilibria of 2-hydroxymethyIarene carbaldehydes and ketones, shows that the change from benzene 34 to the 2,3-disubstituted naphthalene 35 deriva-...

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 C NMR spectra of naphthoxadiazole (6) are consistent with its formulation as a 2,3-disubstituted naphthalene rather than as an o-quinone diazide for example, the lowest field C NMR signal is at 6 148.7 <91AG(E)1476>. 

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). 

Syntheses based not only on compounds 426 but also on other 1,8-disubstituted naphthalenes have been described. Thus, decomposition of peri-diazonium-substituted azides 432 in carbon disulfide, proceeding by the free radical mechanism, yields naphtho[de]-l,3-thiazine-2-thiones 433... 

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. 

Reaction of 102 with a water-soluble 1,4-disubstituted naphthalene (14) leads to a 5,8-endoperoxide (16), in addition to the 1,4-endoperoxide (15) which is normally obtained as the exclusive product in such reactions (in the absence of methyl groups at position 6, 7 or 8).211 Fonnation of the 5,8-isomer is probably due to the effect of steric hindrance of the bulky substituents impairing the approach of102 to the more crowded... 

Tetradehydrodianthracene undergoes 4 + 2-cycloaddition with electron-deficient dienes such as 1,2,4,5-tetrazines.263 The Diels-Alder reactions of [3.3 ortho-anthracenophanes witli A-(p-nitro, chloro, or methoxy-substituted phenyl)malehnides yield approximately equal quantities of inside and outside adducts.264 The photooxidation of bulky water-soluble 1,4-disubstituted naphthalenes with singlet oxygen yields both the expected 1,4- and the unexpected 5,8-endoperoxides.265... 

Strong evidence for the reaction path of the addition of a nucleophile to a carbonyl group comes from the X-ray structure of the naphthalene amino ketone 122 (85). In most 1,8-disubstituted naphthalenes, both substituents are splayed outward (cf. 123). In 122, the C-CO bond is splayed outward, but the C-N bond leans inward (cf. 124). This brings the nitrogen into a more favorable position for attack than is possible in the undistorted molecule. Similar observations were made with the amino ester (122,... 

Synthesis of 1,3-disubstituted naphthalenes is a non-trivial exercise. In an interesting approach to such compounds it was found that they could be assembled by a simple two-step operation as follows. Condensation of 2-(trifluoromethyl)benzaldehyde with pentan-3-one gave the expected aldol product as the (E)-isomer, treatment of which with lithium 4-methylpiperazide in ether at -10°C led directly to l-methylpiperazino-3-propionylnaphthalene in 30% yield. 

Weidmann, B. Seebach, D. MeTi(OiPr)j, a highly selective nucleophilic methylating reagent. Helv Chim. Acta 1980, 63, 2451-2454. Kiefl, C. Mannschreck, A. 1,8-Disubstituted naphthalenes by directed metalation and subsequent Li-Mn exchange, including Cu catalysis. Synthesis 1995, 1033-1037. 

I, 4-disubstituted naphthalene by singlet oxygen. Journal of the Chemical Society,... 

Answer XVI-b is a disubstituted naphthalene [methyi-2-C5-cItloronapiithyi)ketone]. 

Answer XVI-c is a disubstituted naphthalene [2-f5-methoxy-]-naphlliyl)-2-butanol]. 

Haenel et al. investigated [3.3]naphthalenophanes as model systems for excimers [78]. Pyrolysis of the sulfone 257 possessing two 2,6-disubstituted naphthalene units led to a 3 2 mixture of diastereomers consisting of the achiral phane 259 with mirror-symmetry and of a slightly crossed, chiral phane 258. A mixture of a slightly crossed and a clearly crossed phane 261 and 262, respectively, was obtained after pyrolysis of the (2,6)(l,5)sulfone 260. Pyrolysis of 263 containing two 1,4-disubstituted naphthalene units resulted in a 3 2synjantimixture of 264 and 265 [79]. The absorption spectra of the syn and anti isomers show more differences than in the case of the comparable [3.3] or even [2.2]phanes. 

A longer spacer group has also been inserted in the templating molecule by exchanging the 2,6-disubstituted naphthalene spacer of 38 for a 4,4 -biphenyldiyl... 

The anthraquinone 22, naphthalene 23a and the naphthoic acid amide 24 are respective constituents of the bacterial enediyne antibiotics dynemycin A, neocarzinostatin and kedarcidin (Scheme 5). [ C2]acetate feeding studies have established the polyketide origins of the anthraquinone nucleus 22 which is devoid of any carbon substituents and also the rare 1,8-disubstituted naphthalene 23a. ... 

It has been suggested that the anthraquinone 22 may result from the cyclisation of an enediyne rather than a poly-P-ketoacyl heptaketide. If this or any other a non-aldol pathway is involved in the formation of tiie 1,8-disubstituted naphthalene structures 23a and 23b, then the mode F and S classification criteria would not be applicable. 

Among the above wild type streptomycete fused ring fermentation products, only the unusual 1,8-disubstituted naphthalene constituent 23a of the enediyne antibiotic neocarzinostatin provides a possible exception to the predominant S mode of cyclisation. However, the structures recently assigned to two hybrid streptomycete polyketides are similarly not in accord with the classification outlined in Figure 3. 

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