4-Phenyl-1,2-dihydronaphthalene

In 1998, Page and coworkers reported a series of dihydroisoquinoline-related iminium salts which can be readily synthesized in three steps from a chiral amine (Scheme 14) [140-143], Among the catalysts tested for asymmetric epoxidation, iminium salts 74 were found to be efficient catalysts (Fig. 24, Table 7, entries 2, 4-6, 17-19). Iminium salts 74a can epoxidize 4-phenyl-1,2-dihydronaphthalene in up to 63% ee (Table 7, entry 17). 

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). 

Tanner et al. (58) investigated the asymmetric aziridination of styrene using bis(aziridines) such as 85. Low induction is observed with these ligands, Eq. 64. A significant electronic effect was noted with the p-fluoro-phenyl substituted bis(az-iridine) 85c (59). A binaphthyl-derived diamine was used as a ligand for the copper-catalyzed aziridination of dihydronaphthalene (81). The product was formed in 21% ee and 40% yield, Eq. 65. Other structurally related ligands proved to be less selective in this reaction. 

When l,4-dihydronaphthalen-l,4-imine (2) was first obtained via the hydrobromide (113), it was shown to react with phenyl azide to give an adduct (127). The analogous phenyl azide adduct (128) from compound 103 has been better characterized. Naphthalen-l,4-imines also add diazomethane across the 2,3-double bond, forming pyrazolines, e.g., 104 -> 129, two of which have been photolyzed to give the corresponding cyclopropane derivatives (130) with extrusion of nitrogen. ... 

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). 

The binaphthyl-derived iminium-ion catalysts 41a and 41b were introduced by Aggarwal et al. [48a] and Page et al. [48b], respectively (Table 10.7). The highest enantioselectivities reported to date for an iminium-based olefin epoxidation -95% ee using 1-phenyl-3,4-dihydronaphthalene as substrate - were achieved with the catalyst 41b [48b]. 

When ( )-[(/i-arylethyl)vinyl]phenyliodonium tetrafluoroborates are heated in various solvents (at 40 °C or 60 °C), Friedel-Crafts cyclizations occur and dihydronaphthalenes are obtained (equation 26l)127. 6-Bromo-2i7-chromene can be prepared in the same way (equation 262). The alkenylation of benzene with 4-rm-butyl-1 -cyclohexenyl-(phenyl)iodonium tetrafiuoroborate, an intermolecular version of these reactions, has also been demonstrated (equation 263)127. From a stereochemical standpoint, the cyclization reactions are constrained to occur with inversion of configuration at vinyl carbon, while the cyclohexenylation of benzene must proceed with retention. 

Examples of this type include the reactions of 2,6-dimethyl-p-benzoquinone with piperylene (Schmidt, C., Sabnis, S. unpublished results referred to in Liu, T. T. H Schmidt, C. Tetrahedron 27, 5289 (1977)) and 6-methoxy-l-vinyl-2,3-dihydronaphthalene (Dickinson, R. A., Kubela, R McAlpine, G. A., Stojanac, Z Valenta, Z. Can. J. Chem. 50, 2377 (1972)), and the reactions of citraconic anhydride with 1-phenyl-butadiene (Alder, K., Haydn, J.,... 

The reaction rate of the addition decreased on going from phenyl-substituted alkenes to mono-, di-, and trisubstituted alkenes. A preference for E double bonds over Z double bonds was exhibited by the monoimido complex 1. Complete regioselectivity was observed with mono-and trisubstituted alkenes and gmi-disubstituted alkenes, since the C-N bond is formed exclusively at the least substituted alkene carbon, for example of 1-methyl- and 1-phenylcyclo-hexene. However, for 1,2-disubstituted alkenes the regioselectivity depended on the substrate70,71. Unexpectedly, benzylic amination was predominant in the reaction mixtures derived from 1-phenylpropenes and 1,2-dihydronaphthalene (Tabic 5). 

Bulman Page and coworkers have optimized conditions for the use of their 5-amino-2,2-dimethyl-4-phenyl-l,3-dioxane derived imminium salt catalyst 66, and introduced two new analogues (Figure 26) for asymmetric epoxidation. 1-Phenyl cyclohexene and 1-phenyl 3,4-dihydronaphthalene are epoxidized in up to 89% ee <2007JOC4424, 2007T5386>. 

The angular 7a-phenyl hicyclic lactam can he prepared hy the cyclocondensation of 3-henzoylpropionic acid and (S)-valinol in 85% yield. Dialkylation of this lactam also affords cleanly the a,a-disubstituted compound. Lactam hydrolysis releases chiral, nonracemic a,a-disuhstimted y-keto carboxylic esters (or acids) (eq 5) and 3,3-disuhstituted dihydronaphthalenes may he obtained via cyclization. ... 

A minimal structural feature for di-rr-methane rearrangement of acyclic arylpropenes to occur in solution appears to be the presence of an additional phenyl group.A similar requisite seems valid also for cyclic 1,4-systems such as indenes, while the scope for 1,4-dihydronaphthalenes is uncertain. 

Furyl fulgide 20 (Eq. (7)) is the first known example of thermally irreversible photochromic molecules. Although phenyl fulgides such as 21 have been known to show photochromic reactions, photogenerated dihydronaphthalene derivatives such as 21C (Eq. (8)) are thermally unstable and undergo irreversible side reactions, i.e., 1,5-hydrogen shifts to produce 1,2-dihydonaphthalene derivatives [23-26]. This... 

The high efficiency of the present precursor 2 is demonstrated by comparison with a similar precursor, 2-(trimethylsilyl)phenyl triflat (4), which generates benzyne under mild conditions (room temperature and neutral).7 Benzyne precursor 2 gives the adduct, 1,4-epoxy-1,4-dihydronaphthalene 3, quantitatively in the reaction with furan, while the reaction of benzyne precursor 4 under the same conditions leads to a lower yield of adduct 3 and needs longer reaction time. 

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