1.2- Dihydronaphthalene oxide

Addition of amines to 1,2-dihydronaphthalene oxide has been claimed1 1 to yield product corresponding to attack at the epoxide carbon atom furthest from the benzene ring. The validity of this claim... 

Ring dieavage of 1,2-dihydronaphthalene oxide i and 1.4-dibydronaphthalene oxjde < has been carried out with hydrochloric acid and hydrobromio acid respectively. Though it ie safe to suppomr a fruns-Mohydrin to have been formed in the second case (Eq. 726). the product atereocheinistry is somewhat in doubt in the first 726). 

The crude mixture was monitored by chiral stationary phase (CSP) HPLC (eluent hexane/isopropanol 95/5, 0.5mLmin, Chiralcel OD-H). After 2 h, (i/f,25)-l-phenyl-3,4-dihydronaphthalene oxide (80% ee) was obtained as the major enantiomer (fR=13.9 min) with 100% conversion (calculated using the internal standard) the minor 1S,2R) enantiomer eluting first (rR=10.1 min). 

Addition of water to indene oxide,1 1,2-dihydronapMbul[Pg.147]

Epoxides too will react with indoles using Lewis acid catalysis with (l/ ,2 S -l,2-dihydronaphthalene oxide, high enantioselectivity (83% ee) shows the effectiveness of InBrj (Scheme 53) <2002JOC5386>. 

With (li, 23)-l,2-dihydronaphthalene oxide 558 remarkable enantioselectivity was also recorded (ee 83%) showing the effectiveness of InBts in the synthesis of indolyl derivatives 559 in enantiomerically pure form (Equation 133)... 

Kinetic resolution has been reported for dihydronaphthalene oxide and indene oxide upon irradiation in the presence of catalytic amounts of a Ru(salen)(NO) (3) complex (Scheme 10.6) [7]. 

In the context of dihydronaphthalene oxides, Rickborn showed that a related complex induced ring-opening of 257 with SN2 delivery of hydride, Eq. 160 [204]. 

The earliest reports of the addition of organolithium reagents to oxabicydic compounds were in the context of dihydronaphthalene oxide 257. Caple and Berchtold found that the additions occur in an SN2 fashion, leading to alcohols 279a-c,Eq. 176 [211,212],... 

Electrochemical oxidation of 1,2-dihydronaphthalene or an indene in acetoni-tnle containing triethylamine tris(hydrogen fluoride) provides a mixture of tereoisomeric difluorides and vicinal fluoroacetamides [201] (equation 38)... 

Peroxvaad oxidation of bridged 5,6,7,8-tetrafluoro 1 4-dihydronaphthalene-1,4 imines gives aromatic fluorohydrocarbons by elimination of the imine bridge [91] (equation 84) Almost the same yields are achieved by oxidation with 30% hydrogen peroxide m refluxing methanol [91]... 

The formation of an enamine from an a,a-disubstituted cyclopentanone and its reaction with methyl acrylate was used in a synthesis of clovene (JOS). In a synthetic route to aspidospermine, a cyclic enamine reacted with methyl acrylate to form an imonium salt, which regenerated a new cyclic enamine and allowed a subsequent internal enamine acylation reaction (309,310). The required cyclic enamine could not be obtained in this instance by base isomerization of the allylic amine precursor, but was obtained by mercuric acetate oxidation of its reduction product. Condensation of a dihydronaphthalene carboxylic ester with an enamine has also been reported (311). 

I, 4- and 3,4-Dihydroquinazolines are tautomeric but any attempts to prepare the former w ithout a 1-substituent have led to the latter. The greater stability to proto tropic change of 1,2-dihydronaphthalene over 1,4-dihydronaphthalene is also found in 3,4-dihydroquinazoline. Earlier claims to the preparation of l,4-dihydroquinazolines ° were erroneous and based on incomplete experimental data. The first 1,4-dihydroquinazoline was prepared as recently as 1961. 1-Methyl and l-benzyl-l,4-dihydroquinazolines were obtained from o-methylamino-and o-benzylamino-benzylamines (42) by formylation and ring closure. Attempts to remove the benzyl group gave 3,4-dihydroquinazoline. These 1,4-dihydro compounds are susceptible to oxidation, and attempts made to prepare 1,2-dimethyl-1,4-dihydroquinazoline from o-... 

The oxidation of 1,4-dihydronaphthalene with oxygen with irradiation gave l,2-dihydro-2-naphthyl hydroperoxide that decomposed thermally to 3-benzoxepin (3).189... 

Asymmetric epoxidation of olefins with ruthenium catalysts based either on chiral porphyrins or on pyridine-2,6-bisoxazoline (pybox) ligands has been reported (Scheme 6.21). Berkessel et al. reported that catalysts 27 and 28 were efficient catalysts for the enantioselective epoxidation of aryl-substituted olefins (Table 6.10) [139]. Enantioselectivities of up to 83% were obtained in the epoxidation of 1,2-dihydronaphthalene with catalyst 28 and 2,6-DCPNO. Simple olefins such as oct-l-ene reacted poorly and gave epoxides with low enantioselectivity. The use of pybox ligands in ruthenium-catalyzed asymmetric epoxidations was first reported by Nishiyama et al., who used catalyst 30 in combination with iodosyl benzene, bisacetoxyiodo benzene [PhI(OAc)2], or TBHP for the oxidation of trons-stilbene [140], In their best result, with PhI(OAc)2 as oxidant, they obtained trons-stilbene oxide in 80% yield and with 63% ee. More recently, Beller and coworkers have reexamined this catalytic system, finding that asymmetric epoxidations could be perfonned with ruthenium catalysts 29 and 30 and 30% aqueous hydrogen peroxide (Table 6.11) [141]. Development of the pybox ligand provided ruthenium complex 31, which turned out to be the most efficient catalyst for asymmetric... 

Similarly, 1-vinylcyclohexane can be trapped with dimethyl acetylenedicarboxylate in refluxing xylene to afford 195 in 78% yield (equation 126)119. Benzo[ ]anthracene can be obtained by the reaction of 196 and 1,2-dihydronaphthalene (equation 127) and oxidation of 197 with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone120. 

Compounds lb and 2b were the Urst fluorinated ligands tested in Mn-catalyzed alkene epoxidation [5,6]. The biphasic Uquid system perfluorooc-tane/dichloromethane led to excellent activity and enantioselectivity (90% ee) in the epoxidation of indene with oxygen and pivalaldehyde (Scheme 1, Table 1). In addition, the fluorous solution of the catalyst was reused once and showed the same activity and selectivity. This represents a considerable improvement over the behavior in the homogeneous phase, where the used catalyst was bleached and reuse was impossible. Unfortunately, indene was the only suitable substrate for this system, which failed to epoxidize other alkenes (such as styrene or 1,2-dihydronaphthalene) with high enantioselectivity. The system was also strongly dependent on the oxidant and only 71% ee was obtained in the epoxidation of indene with mCPBA at - 50 °C. 

Eaton SL, SM Resnick, DT Gibson (1996) Initial reactions in the oxidation of 1,2-dihydronaphthalene by Sphingomonas yanoikuyae strains. Appl Environ Microbiol 62 4388-4394. 

Heterocycles Both non-aromatic unsaturated heterocycles and heteroaromatic compounds are able to play the role of ethene dipolarophiles in reactions with nitrile oxides. 1,3-Dipolar cycloadditions of various unsaturated oxygen heterocycles are well documented. Thus, 2-furonitrile oxide and its 5-substituted derivatives give isoxazoline adducts, for example, 90, with 2,3- and 2,5-dihydro-furan, 2,3-dihydropyran, l,3-dioxep-5-ene, its 2-methyl- and 2-phenyl-substituted derivatives, 5,6-bis(methoxycarbonyl)-7-oxabicyclo[2.2.1]hept-2-ene, and 1,4-epoxy-l,4-dihydronaphthalene. Regio- and endo-exo stereoselectivities have also been determined (259). 

The catalyst efficiency of these hydroalumination varies from a turnover number (TON) of 20-91. It is possible that the catalyst is deactivated by the presence of oxygen and water. Examination of the 31P NMR spectrum of the catalyst indicates that the phosphine monoxide and dioxide are formed in the presence of nickel prior to the addition of the substrate. Rigorous exclusion of oxygen and water is necessary in all these reactions. The enantioselective nickel-catalyzed hydroalumination route to dihydronaphthalenols may prove to be particularly important. Only one other method has been reported for the enantioselective syntheses of these compounds microbial oxidation of dihydronaphthalene by Pseudomonas putida UV4 generates the dihydronaphthalenol in 60% yield and >95% ee.1... 

Cycloaddition (13,326).2 The azomethine ylide (a) generated with LDA from trimethylamine oxide adds stereoselectively to the dihydronaphthalenes 1 to provide the benzisoindoiines 2, of use as a-adrenergic agents in therapy. 

Wilson and Madsen [152] used the metabolic pathway for bacterial naphthalene oxidation as a guide for selecting l,2-dihydroxy-l,2-dihydronaphthalene as a unique transient intermediary metabolite whose presence in samples from a contaminated field site would indicate active in situ naphthalene biodegradation (Fig. 26). Naphthalene is a component of a variety of pollutant mixtures. It is the major constituent of coal tar [345], the pure compound was commonly used as a moth repellant and insecticide [345], and it is a predominant constituent of the fraction of crude oil used to produce diesel and jet fuels [346]. Prior studies at a coal tar-contaminated field site have focused upon contaminant transport [10,347], the presence of naphthalene catabolic genes [348, 349], and non-metabolite-based in situ contaminant biodegradation [343]. 

The final stage of the reaction in Scheme 3.65 involves protonation, yielding the derivative of 1,4-dihydronaphthalene. The oxidation may produce a 4-substituted binaphthyl, which is not contaminated with the isomeric products. It is worth noting here that the described ion-radical method of introduction of the alkyl group into the aromatic nucleus has an advantage over the radical or heteroly tic alkylation. In these cases, the neutral substrate may produce a composite mixture of isomeric products. The binaphthyl anion-radical reaction proceeds regioselectively and nonstereospecifically. 

The effect of structural variation and the use of different caboxylate salts as cocatalysts was investigated by Pietikainen . The epoxidation reactions were performed with the chiral Mn(III)-salen complexes 173 depicted in Scheme 93 using H2O2 or urea hydrogen peroxide as oxidants and unfunctionalized alkenes as substrates. With several soluble carboxylate salts as additives, like ammonium acetate, ammonium formate, sodium acetate and sodium benzoate, good yields (62-73%) and moderate enantioselectivities (ee 61-69%) were obtained in the asymmetric epoxidation of 1,2-dihydronaphthalene. The results were better than with Ai-heterocycles like Ai-methylimidazole, ferf-butylpyridine. 

Af-methylmorpholine A-oxide or 4-phenylpyridine A-oxide as cocatalysts. The yields and enantioselectivities obtained with HgOg or urea hydrogen peroxide were comparable, with slightly better yields for the epoxidation with HgOg (73% versus 68% for the epoxide of 1,2-dihydronaphthalene in the presence of NH4OAC). 

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