Dihydronaphthalene trans

The photochemically allowed [<72, +, 4 ] or [(,2a +, 4J pathways are also well documented, for example Equation (6.29). The cleavage processes are also known, and if these processes are followed by recychzation under purely thermal control, then cis-trans isomerizations have been observed, e.g. Equation (6.30). A similar reaction sequence has been proposed for the photoisomerization of trans-9,10-dihydronaphthalene to the cir-isomer, in which... 

Many other examples of contrasting behaviour have been discovered. For example all-cis-cyclodecapentaene (VII) photochemically equilibrate at low temperatures with trans 9, 10 dihydronapthalene by a conrotatory six electron electrocyclic reaction but it is converted thermally into cis-9, 10 dihydronaphthalene by disrotatory closure. 

Chiral-trans-l,2-disubstituted-l,2-dihydronaphthalenes (cf. 12, 310-311).1 Addition of an organolithium to chiral (l-naphthalyl)oxazolines (2, derived from 1) followed by quenching with CF3COOH results in the salt 3. This product is reduced by LiAlH4 to a single frans-l,2-diaxial diastereomer 4. 

On the contrary, the m-benzenedihydrodiol is found to react 4500 times more rapidly in the presence acid than the trans. Moreover, as shown below, this ratio falls to 440 for naphthalene dihydrodiols, to 50 for phenanthrene dihydrodiols, and less than 10 for a nonaromatic analog such as the acenaphthylene or dihydronaphthalene dihydrodiols.164 These rate ratios are shown on the following page and suggest that the effect is linked to the aromaticity of the ultimate product of the reaction. Trapping experiments with the 10-hydroxyphenanthrenonium ion 31 indicate that the ratio of... 

This possibility of intimate association of rhodium with the aromatic ring suggests further experiments. A logical extension of asymmetric syntheses involving prochir-al reactants is a kinetic resolution with related chiral reactants under similar conditions. In the one case of hydroboration-amination where this has been applied, it has proved to be very effective. The reactant was prepared directly by a Heck reaction on 1,2-dihydronaphthalene, and under the standard conditions of catalytic hydrobora-tion gave >45% of both enantiomerically pure recovered alkene with (after oxidative work-up) the alcohol of opposite hand, mainly as the trans-isomer. This procedure forms a simple and potentially useful route to pharmacologically active substances, demonstrated by the racemic synthesis shown [105] (Scheme 34). 

Naphthalene is reduced to 1,4-dihydronaphthalene by sodium and alcohol. Isomerization of this product to 3,4-dihydronaphthalene occurs with sodamide in liquid ammonia. Tetrahydronaphthalene (tetralin) is formed from naphthalene by sodium in amyl alcohol or by reduction with nickel-aluminum alloy and aqueous alkali. Catalytic hydrogenation of naphthalene can be stopped at the tetralin stage over copper chromite, Raney nickel, or alkali metal catalysts. cis-Decahydronaphthalene is produced by high-pressure hydrogenation of tetralin over Adams catalyst, whereas a mixture of cis- and trans-decalins is obtained from naphthalene under the same conditions. ... 

Further studies and numerous synthetic applications of the photocyclization of enamides have been reported. Irradiation of JV-methyl- and JV-benzyl-cyclohex-l-enecarboxanilide (20) affords a mixture of cis- (21) and trans-phen-anthridones (22).17 JV-Methyl-3,4-dihydronaphthalene-l-carboxanilide is analogously converted into the corresponding benzophenanthridones. Formation of... 

Diels-Alder Reactions. Bp3-OEt2 is used to catalyze and reverse the regiospecificity of some Diels-Alder reactions, e.g. with pen-hydroxylated naphthoquinones, sulfur-containing conpounds, the reaction of 1-substituted trans-1,3-dienes with 2,6-dimethylbenzoquinones, and the reaction of 6-inethoxy-l-vinyl-3,4-dihydronaphthalene with p-quinones. BFs-OEta has a drastic effect on the regioselectivity of the Diels-Alder reaction of quinoline- and isoquinoline-5,8-dione with piperylene, which produces substituted azaanthraquinones. This Lewis acid is the most effective catalyst for the Diels-Alder reaction of furan with methyl acrylate, giving high endo selectivity in the 7-oxabicyclo[2.2.1]heptene product (eq 35). ... 

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