16606-46-5

We report a hydrogen-evolution dimerization of styrenes via the synergistic merger of Acr+-Mes photocatalyst and cobaloxime proton reduction catalysts. By utilizing this dual catalyst system, 1,2-dihydro-1-arylnaphthalene derivatives can be directly constructed from commercially available styrenes. Our reaction proceeds smoothly under mild conditions without the need for oxidants or hydrogen atom transfer reagents, and the sole byproduct is hydrogen gas. Mechanistic investigation suggests that the reaction is initiated by photoinduced electron transfer under visible-light irradiation.

A variety of functionalized triarylmethane and 1,1-diarylalkane derivatives were prepared via a transition-metal-free, one-pot and two-step procedure, involving the reaction of various benzal diacetates with organozinc reagents. A sequential cross-coupling is enabled by changing the solvent from THF to toluene, and a two-step SN1-type mechanism was proposed and evidenced by experimental studies. The synthetic utility of the method is further demonstrated by the synthesis of several biologically relevant molecules, such as an anti-tuberculosis agent, an anti-breast cancer agent, a precursor of a sphingosine-1-phosphate (S1P) receptor modulator, and a FLAP inhibitor.

A protocol for palladium-catalyzed dearomative functionalization of simple, nonactivated arenes with Grignard reagents has been established. This one-pot method features a visible-light-mediated [4+2] cycloaddition between an arene and an arenophile, and subsequent palladium-catalyzed allylic substitution of the resulting cycloadduct with a Grignard reagent. A variety of arenes and Grignard reagents can participate in this process, forming carboaminated products with exclusive syn-1,4-selectivity. Moreover, the dearomatized products are amenable to further elaborations, providing functionalized alicyclic motifs and pharmacophores. For example, naphthalene was converted into sertraline, one of the most prescribed antidepressants, in only four operations. Finally, this process could also be conducted in an enantioselective fashion, as demonstrated with the desymmetrization of naphthalene.

We report a radical cation [4+2] annulation of arylalkenes to afford naphthalene derivatives using an organic photosensitizer (9-mesityl-10-methylacridinium perchlorate) under visible light photocatalysis. In the presence of oxygen (in the air), the oxidative dimerization/intramolecular [4+2] cycloaddition of two alkene molecules provides 3,4-dihydronaphthalen-1(2H)-ones in good to high yields. Under a nitrogen atmosphere, (dihydro)naphthalenes were attained in moderate to excellent yields by using Selectfluor as the oxidant. The transformation proceeds via a tandem dimeric electrophilic addition/Friedel–Crafts cyclization/radical coupling/elimination sequence. This approach represents a mild and straightforward assembly of the naphthalene skeleton using a visible light photocatalytic cascade strategy. (Figure presented.).

Mixed trifluoroacetyl phenylacetyl anhydride and 3-halostyrenes (fluoro, chloro, and bromo) or vinylcycloalkanes (cyclohexyl and cyclooctyl), undergo cascade Friedel-Crafts cycli-acylalkylation, enolization, and O-acylation to give 4-substituted tetralen-

Polycondensation of naphthalene and its alkyl derivatives (stripping oil, 2,5-dimethylnaphthalene) in the presence of aluminum halides was performed. Under the action of an ultrasonic field on a benzene solution of naphthalene in the presence of the catalyst, intermolecular condensation and benzene addition are observed.

Irradiation of 9,10-dicyanoanthracene (DCA) or p-chloranil in the presence of E-1-benzylidene-2-phenylcyclopropane (E-5) in CH2CI2 causes E-5 to undergo methylenecyclopropane rearrangement. An adduct, Z-7, between DCA and 5 firmly supports the involvement of a bifunctional trimethylenemethane radical cation. In contrast, incorporation of E-5 into HZSM-5 produces trans,trans-1,4-diphenyl-1,3-butadiene radical cation sequestered in the HZSM-5 interior, tt-8·+ @ HZSM-5, identified by ESR and diffuse reflectance spectroscopy. In addition, low yields of tt-8, its cis, trans-isomer (ct-8), and 1-phenyl-1,2-dihydronaphthalene (9) were isolated from the supernatant solution. The sharp contrast between the photoinduced electrontransfer reaction with photosensitizers in solution and the spontaneous reaction with redox-active acidic zeolite offers the prospect of further zeolite-induced regiodivergent reactions in a range of additional substrates.

The Heck reaction of aryl iodides with 1,2-dihydronaphthalene has been examined. Two separate reaction pathways are observed under all the conditions tried. Arylation adjacent to the aromatic ring leads to a subsequent double bond shift such that the product is a 1-aryl-1,2-dihydronaphthalene. The alternative regiochemistry leads to production of the corresponding 3-aryl-1,2-dihydronaphthalene, and labelling studies with specifically deuterated alkenes demonstrate that this is most likely to be the result of a trans Pd-H elimination pathway. The ratio always varies between 75:25 in favour of the 3-aryl product (Jeffery conditions) to 70:30 in favour of the 1-aryl product.

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The thermal rearrangement of the four phenyl-substituted 1,2-dihydronaphthalenes (15), (16), (19), and (20) have been studied by flash vacuum pyrolysis (FVP).By using the deuteriated starting compounds -(15) and -(16), it has been established that 1- and 4-phenyl-1,2-dihydronaphthalene (15) and (19) and 2- and 3-phenyl-1,2-dihydronaphthalene (16) and (20) are interconverted via the intermediates 1- and 2-phenyl-2,3-dihydronaphthalene (17) and (18), respectively, through two consecutive, sigmatropic 1,5-hydrogen shifts.In both processes partial oxidation to the corresponding phenylnaphthalenes (21) and (22) takes place.The deuterium distribution in the pyrolysis products suggests that in the hot zone diphenylbutadienes are formed, which are reconverted into phenyldihydronaphthalenes upon reaching the cold receiving flask.By FVP of 4-(p-tolyl)-1,2-dihydronaphthalene (34), 1-phenyl-1-(p-tolyl)butadiene (39), and 1-phenyl-4-(p-tolyl)butadiene (45) the latter type of interconversion could be confirmed.

The thermal rearrangements of benzobicyclohex-2-ene (21) and its phenyl-substituted analogues 22-25 (Scheme V) as models of sterically constrained phenylcyclopropanes have been studied by means of flash vacuum pyrolysis.In most cases the major pathway was cleavage of the "internal" C(1)-C(5) cyclopropane bond followed by a 1,2-hydrogen or a 1,2-phenylshift in the resulting biradical.For 6-phenylbenzobicyclohex-2-ene (25), substantial cleavage of the "external" C(1)-C(6) cyclopropane bond was observed, the phenyl substitution pattern being favorable for stabilization of the resulting biradical 62.Phenyl-substituted 1,2-dihydronaphthalenes 44, 47, 51, and 55 are among the major products.Comparison of the plots of the pyrolysis product composition of the 1,2-dihydronaphthalenes vs. pyrolysis temperature with similar plots of the title compounds (22-25) suggested that some of the minor products, viz., the 1,2-divinylbenzenes 31, 42, and 49, are formed via carbenes 30, 41, 50, 57, and 61 rather than via biradicals.Especially at higher pyrolysis temperatures, a large amount of an oxidation product, viz., 1- or 2-phenylnaphthalene (48 or 54), is formed.

The photochemical rearrangements of phenyl-substituted benzobicyclohex-2-enes can generally be explained by assuming that homolytic fission of that cyclopropane bond which leads to the most stable diradical is the primary step.The final products are formed by 1,2 hydrogen shifts in the intermediate.An exception to this general pattern was observed with 5-phenylbenzobicyclohex-2-ene (5).The photoproducts of 5 could only be explained by assuming reverse di-?-methane rearrangements followed by 1,3 hydrogen shifts.It is argued that this reaction path is followed because of the high rate to the back-reaction of the homolytic bond fission of 5.

The synthesis of variously substituted 3-methoxycarbonylindene and 4-methoxycarbonyl-1,2-dihydronaphthalenes is described.A simple and efficient method for the transformation of 1-tetralone into 2-tetralone is reported.

Addition of 2,2-diphenyl-1-picrylhydrazyl DPPH to styrene at 75 deg C results in little change in the amounts of cis- and trans-1,2-diphenylcyclobutane and 1,2,3,4-tetrahydro-1-phenylnaphthalene, in a slightly smaller amount of 1-phenylnaphthalene, and in a considerable increase in the amount of 1,2-dihydro-1-phenylnaphthalene that are formed.Formation of the styrene trimer 1,2,3,4-tetrahydro-1-phenyl-4-(1-phenylethyl)naphthalene is eliminated completely.Products derived from DPPH are 1-(4-nitrophenyl)-1-phenyl-2-picrylhydrazine 9 and 1--2,2-diphenylhydrazine, 10.DPPH intercepts the thermally formed Diels-Alder dimer of styrene as soon as it is formed to give the 1,2,3,4-tetrahydro-4-phenyl-1-naphthyl radical.Thermolysis of bis(1,2,3,4-tetrahydro-4-phenyl-1-naphthyl)diazene in the presence of DPPH yields 20percent of 10, 10percent of 1--2-(4-nitrophenyl)-2-phenylhydrazine and 9 while thermolysis of 1,2-bis(1-phenylethyl)diazene in the presence of DPPH yields 9 and 44percent of 1--2,2-diphenylhydrazine showing that substituted benzyl radicals efficiently displace the 4-nitro group of DPPH.The nitro group is transferred to an unsubstituted phenyl group of DPPH.

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