Naphthalene-diene derivatives

CD Spectra of Naphthalene-Diene Derivatives with Twisted n-Electron System... 

Figure 3. NOE data and conformation of naphthalene-diene derivative (-i-)-23.18...

Application of the Jc-Electron SCF-CI-DV MO Method to Naphthalene-Diene Derivatives... 

As discussed above, the absolute stereochemistry of halenaquinone (+)-l and halenaquinol (+)-2 has been theoretically determined by the calculation of the CD spectra of naphthalene-diene derivatives by means of the tt-electron SCF-CI-DV MO method. 18 To apply the same method to these xestoquinone compounds, xesto-quinol dimethyl ether (+)-74 was converted to naphthalene-diene derivative 75 by reduction with sodium borohydride in the presence of cerium(IIl) chloride23 and methanol, followed by treatment with pyridinium p-toluenesulfonate and methanol (Scheme 16).20 The product obtained was a mixture of two stereoisomers of the methoxyl group at the 4-position, from which a single isomer 75 was isolated as... 

Figure 14. CD and UV spectra of xestoquinol naphthalene-diene derivative (4, 12bS)-75 in CH3CN.20...

The absolute stereostructures of halenaquinone (+)-l, halenaquinol (+)-2, halenaquinol sulfate (-i-)-3, xestoquinone (+)-4, and xestoquinol 62, novel pentacyclic marine natural products isolated from tropical marine sponges, were theoretically determined to be 12bS, respectively, on the basis of the calculation of the CD spectra of naphthalene-diene derivatives by the re-electron SCF-CI-DV MO method. These studies also clarified that the theoretical CD method was applicable to such complex natural products. 

The naphthalene-diene compounds (-)-22 and (+)-23 were also derived directly from halenaquinol dimethyl ether (+)-17 by the reduction and subsequent terr-butyldimethylsilylation (Scheme 3). Diketone (-i-)-17 was reduced and then treated with hydrochloric acid, as in the case of ketone (+)-19 of Scheme 2, giving rranj-methoxy alcohol (-)-24 and cj j-methoxy alcohol (-)-25, respectively. Each alcohol was then converted to its /ert-butyldimethylsilyl ether, which was identical with the authentic sample derived from compound (+)-19. 

It was quite interesting that naphthalene-diene compounds (-)-22, (-t-)-23, (-)-24, and (-)-25 exhibited much stronger CD Cotton effects than other halenaquinol derivatives. For example, the UV spectrum of rra j-methoxysilyl ether (-)-22 shows two intense n- K bands (Figure 4) the broad band at 324 nm (e 27 000) with complex vibrational structures and the sharp band at 218 nm (e 42 000). In... 

Reaction of 1,4-dilithio-l,3-dienes 1 with 1.1 or 1.2 equiv of CeFe at room temperature afforded the multi-substituted partially fluorinated naphthalene derivatives 2/6 in good to high isolated yields (Scheme 12) [56]. The reaction is assumed to proceed via double nucleophilic substitution. The naphthalene derivatives with different substitution patterns could be prepared conveniently by this method. Instead of nucleophilic substitution, when di-lithio reagents 1 were treated with hexachlorobenzene, chloropentafluorobenzene, or bromopentafluorobenzene, chlorine-lithium or bromine-lithium exchange reactions took place to afford the 1,4-dichloro- or 1,4-dibromo-l,3-diene derivatives. Preliminary results demonstrate that these partially fluorinated multi-substituted naphthalene derivatives show unique stacking fashions. 

Generally, benzene and naphthalene derivatives show only little reactivity as dienes in Diels-Alder synthesis, contrary to anthracene and the higher acene derivatives which are frequently used as dienes. Exceptions are the reactions of benzene and naphthalene derivatives with highly reactive dienophiles such as dicyanoacetylene (DCA), which... 

Less complex non-conjugated diene systems also lead to cubane-like derivatives as in the diene 175. Here the outcome of the reaction is dependent upon the excited state. Thus, direct irradiation brings about fragmentation with the formation of 1,4-difluorobenzene and excited-state naphthalene while triplet-sensitized irradiation follows a different path with the formation of the cage compound 17682. 

Polyfluorinatcd benzenes, naphthalenes or pyridines react with the salts C1F2 + BF4 , BrF2 + BF4 , BrF2+SbF6 , BrF4 Sb2F, 1 to give fluorinated derivatives of cyclohexa-1,4-diene, cyclohexene, 1,4-dihydronaphthalene, or 2,3-dihydropyridine.141... 

Tsuge and co-workers - building on work by Bailey and Blomquist [5] - have already made extensive use of the preparative potential of these so-called diene transmissive Diels-Alder additions (DTDA additions) [8]. Clearly, the dienophile does not have to be identical in the two stages of the reaction, which increases the preparative potential of these double cycloadditions considerably. The adducts of type 22 can be further processed in various ways, for example by dehydrogenation to give 1,2,6,7-tetrasubstituted naphthalene derivatives as will be discussed below. Consecutive reactions of this type with their excellent atom economy are of considerable interest particularly in view of the current efforts to increase the efficiency of organic transformations. 

Having sufficient amounts of these novel dienes in hand opens the field for further study. Cycloaddition of acetylenedicarboxylic acid dimethyl ester (ADDE) to [3]dendralene 7 in toluene first afforded the l l-adduct 43, which by a second addition of ADDE provided the expected 2 l-adduct 44. After this had been aromatized by treatment with DDQ to the naphthalene derivative 45, a double benzannulation could be carried out as described in Scheme 8 [13]. 

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

The 1,2- and 1,4-addition reactions have been observed also for alkyl-substituted aromatics, but the yields are often low, in particular for benzene derivatives, owing to competing side-chain substitution reactions. Examples include the addition of MeOH to methyl-substituted benzenes [38-42], naphthalenes [43], and anthracenes [43,44]. In a similar fashion, the anodic oxidation of 1,3-dienes in MeOH [45,46] results in mixtures of 1,2- and 1,4-addition products accompanied by substitution products and methoxy-containing dimers and trimers [46]. Styrenes are oxidized in MeOH to the 1,2-addition product together with products formed by dimerization-addition [47,48]. Oxidation of allenes results in most cases in complicated product mixtures resulting from single and double addition reactions [49-52]. 

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