1.4- Dihydronaphthalene preparation

Experimental studies have indicated that all of the isomers prepared to date are quite reactive, but whether the most stable isomer has been observed is uncertain. Two of the isomeric [lOJarmulenes, as well as other products, are formed by photolysis of c/s-9,10-dihydronaphthalene ... 

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 dihydronaphthalene-annelated pyranylidene complex 178, prepared according to reaction route E in Scheme 4 from /J-tetralone and complex 35, upon treatment with the pyrrolidinocyclopentene 174 n-1) or -cyclohexene 174 (n=2) at room temperature gave the tetracyclic compounds 179 in excellent... 

As for compounds having modified bridges in a bicyclo[2.2.2]octatriene system, 1 -rm-butyl-1,4-dihydronaphthalene 1,4-endoxides (109) and 9-rm-butyl-l,2,3,4-tetrachloro-9,10-dihydro-9,10-ethenoanthracene (110) were prepared. The... 

PREPARATION OF CYANO COMPOUNDS USING ALKYLALU-MINUM INTERMEDIATES. II. l-CYANO-6-METHOXY-3,4-DIHYDRONAPHTHALENE, 52, 96... 

The present method developed by the submitters is the only practical process for preparation of l-cyano-6-methoxy-3,4-dihydronaphthalene. Birch and Robinson have reported that 6-methoxy-l-tetralone did not react with hydrogen cyanide or sodium acetylide. 

This process presents a typical procedure applicable to preparation of cyanohydrins from ketones and aldehydes of low reactivity. l-Cyano-6-methoxy-3,4-dihydronaphthalene is useful as an intermediate for synthesis of polycyclic compounds. 

Since different reactivity is observed for both the stoichiometric and the catalytic version of the arene-promoted lithiation, different species should be involved in the electron-transfer process from the metal to the organic substrate. It has been well-established that in the case of the stoichiometric version an arene-radical anion [lithium naph-thalenide (LiCioHg) or lithium di-ferf-butylbiphenylide (LiDTBB) for using naphthalene or 4,4 -di-ferf-butylbiphenyl (DTBB) as arenes, respectively] is responsible for the reduction of the substrate, for instance for the transformation of an alkyl halide into an alkyllithium . For the catalytic process, using naphthalene as the arene, an arene-dianion 2 has been proposed which is formed by overreduction of the corresponding radical-anion 1 (Scheme 1). Actually, the dianionic species 2 has been prepared by a completely different approach, namely by double deprotonation of 1,4-dihydronaphthalene, and its X-ray structure determined as its complex with two molecules of N,N,N N tetramethylethylenediamine (TMEDA). ... 

Various 1-(1-naphthyl)-1,2,3-triazoles with electron-withdrawing groups at the 4- and/or 5-pos-itions (e.g. (135)) are synthesized from 1-azidonaphthalene and alkynes <87JCS(P1)413>. l-(Naphthyl)-benzotriazoles (127) are prepared by cycloaddition of the appropriate 1-azidonaphthalenes to benzyne or substituted benzynes, generated from 3-methylanthranilic acid. l-(l-Naphthyl)-naphthotriazole is similarly prepared by cycloaddition to 2,3-dihydronaphthalene. 1,3-Dipolar cycloadditions of 8-azidoquinolinone with benzyne and DMAD give benzotriazoles and triazoles (e.g., (130)), respectively <87JCS(Pi)403>. 

Oxazoline-directed conjugate addition of nucleophiles to a naphthalene nucleus is one of the most useful methods to prepare dihydronaphthalenes. Since Meyers last comprehensive review, the focus has been directed to stereoselective synthesis of these important compounds. Meyers laboratory has continued their preeminence in this field and has expanded the scope and applications of this reaction. 

M 2-Fluoro-3,4-dihydronaphthalen-l(2//)-one in cyclohexane (18 mL) containing a molar equivalent amount of Et3N was irradiated in a quartz tube for 15 h with254-nm light. The solvent was then evaporated in vacuo and the crude product was purified by preparative GC (OV 17 on Chromosorb W AW). 

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). 

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. 

When the vinyldiazoacetate 19, which can be prepared from benzaldehyde in a one-pot process,6 was treated in 2,2-dimethylbutane (DMB) with dirhodium tetrakis[(,S )-7V-(dodccylbenzcncsulfonyl)prolinate] [Rh2(S -DOSP)4] in the presence of 4-methyl or 4-trimethylsilyloxy-l,2-dihydronaphthalene (20), the product 21 was obtained with exceptionally high levels of enantio- and diastereo selectivity7 (Scheme 1.4f). 

Tubulin-binding agents prepared by Pinney (4) consisting of dihydronaphthalene derivatives, (IV), exhibited potent tumor cell cytotoxicity by inhibiting the polymerization of a,(3-tubulin heterodimers into the microtubule structures and were used in the treatment of proliferation diseases. 

The use of im-butyl /V./V-dichlorocarbamate allows the preparation of the corresponding A -Boc-protcctcd amines, from which the free amines can be conveniently obtained by mild acidic treatment. The addition to indene, and 1,2-dihydronaphthalene and benzopyran derivatives gave exclusively the tram-adducts, from which amines, diamines, aziridines, and oxazo-lidinones were in turn prepared79. 

Yang and co-workers have suggested that the inherent difficulties in the preparation/isolation of unstable exocyclic iminium salts can be overcome by in situ formation of the catalytic species from chiral pyrrolidines and aldehydes. The catalytic asymmetric epoxidation of phenylcyclohexene and dihydronaphthalene mediated by the iminium salt derived from pyrrolidine 67 and aldehyde 68 has been examined (Scheme 27) <20010L2587>. 

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. ... 

The preparation of annelated tetrakisdehydro[18]annulenes 349 and 350 and the reference dehydroannulene 351 afforded further insight into the 7t-electron delocalization in annelated annulenes . When a dihydronaphthalene nucleus in 351 was replaced by naphthalene to form the annelated dehydroannulene 350, an appreciable suppression of diatropicity in 350 was observed. Further replacement of the dihydronaphthalene by naphthalene to give the dinaphtho-annelated derivative 349 resulted in a further suppression of the diatropicity in contrast to the increase of diamagnetic ring current in the case of transition from 342 to 340 and from 343 to 341. 

Benzoxepin 12 has been prepared by methods similar to those already discussed for arene oxides. Thus photochemical isomerization of l,4-epoxy-l,4-dihydronaphthalene to an oxaquadricyclane intermediate followed by thermal... 

Diphenylpicrylhydrazyl, which is prepared from MA -diphenyl-A -(2,4,6-trinitrophenyl)hydrazine by oxidation with lead dioxide [982], is used for the dehydrogenation of 1,4-dihydronaphthalene to naphthalene and of hydrazobenzene to azobenzene [983]. Simpler and cheaper compounds are, however, available for such purposes (equation 21). 

Compounds like 1,4-dihydronaphthalene, tetralin, and decalin, which contain the carbon skeleton of an aromatic system but too many hydrogen atoms for aromaticity, are called hydroaromatic compounds. They are sometimes prepared, as we have seen, by partial or complete hydrogenation of an aromatic system. 

Diels-Alder dienophiles a-Acetoxyacrylonitrile. Acetylenedicarboxyhc acid. Acrolein (see 1-o-Nitrophenylbutadiene). Allyl alcohol (see Lithium). 1,4-Benzoquinone (see also 1,4-Naphthoquinone, preparation). /rans-l,2-Dibenzoylethylene. Di-(-butyl azodiformate. Dichloroketene. Dicyanoacetylene. Diethyl acetylenedicarboxylate. 1,4-Dihydronaphthalene-... 

Reaction of l,4-dihydronaphthalene-l,4-imine with di-pyridyl-1,2,4,5-tetrazine, designed to prepare isoindoles, also gives 3,6-di-pyridyl-pyridazine. Other bicyclic alkenes react similarly. Pyridazines are also formed in reactions between 1,2,4,5-tetrazines and dioxene. 

B36. Booth, J., Boyland, E., Sato, T., and Sims, P., Metabolism of polycyclic compounds. 17. Reaction of 1 2-dihydronaphthalene and l 2-epoxy-l 2 3 4 tetra-hydronaphthalene with glutathione catalysed by tissue preparations. Biochem. J. 77, 182-186 (1960). 

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