Octalins, formation

Octalin formation was dependent on the tetralin conversion and, thus, only indirectly dependent on deactivation. The deactivation did not have a significant effect on stereochemistry (cw-/ra s-distribution) change in the isomer distribution was observed only in the longest run (about 71 h), in which the deactivation was also most severe. 

A " -octalin was detected in measurable amount almost immediately after tetralin was observed, whereas no more than traces of A -octalin were detected, and in only a few experiments. Octalin formation was highly dependent on tetralin A " -octalin formation was favoured with the high concentration and conversion of tetralin that typically occurred at high temperature with high initial naphthalene concentration. 

A concerted four-center cis addition leads to (52) and a trans adduct a trans addition, possibly via protonium species, leads to (53) and a cis adduct a stepwise cationic addition leads to (54) and a mixture of cis and trans adducts. Recent studies by Marshall and Wurth strongly indicate that intermediate (54) is correct. Irradiation of octalin (55) in aqueous /-butyl alcohol (DaO)-xylene results in formation of the equatorially deuterated alcohols (56) and (57) and the equatorially deuterated exocyclic olefin (58) ... 

The dienaldehyde 117 cyclizes to a mixture of the octalins 120 and 121 on treatment with concentrated orthophosphoric acid. It was suggested that the reaction is initiated by formation of the cation 118, which undergoes ring-closure to the bicyclic cation 119. Proton loss in two alternative ways leads to the products (equation 62)72. 

Treatment of trans,trans-2,6-ociddiene (122) with deuteriated formic acid HCO2D in the presence of deuteriosulphuric acid gave the cyclized formate ester 123. A concerted mechanism (equation 63) was proposed for this reaction73. The stereospecific ring-closure of the 1,4-cyclohexadiene derivative 124 in acetic anhydride/perchloric acid affords the octalin 125, which was isolated as the diacetate 126 (equation 64)74. 

Another example of the formation of an octalin is the conversion of the cyclohexenone 127 into the enol acetate 128 by the action of acetic anhydride and perchloric acid in the presence of acetic acid (equation 65)75. The acid-induced ring-closure of the cyclopentane derivative 129 gives a 85% yield of a mixture of the octahydroazulenes 130 and 131... 

ESR spectra for, 22 294, 301 as high-energy fuels, 18 2-4 hydrogenation course of, 18 6-8 equilibria, 18 7, 8 kinetic processes, 18 6, 7 experimental procedures, 18 19, 20 apparatus and methods, 18 20 materials, 18 20 mechanism of, 18 21-45 formation of isomeric decahydro-naphthalenes, 18 23-30 deuterogena-tion of - -octalin, 18 29 routes to trans isomers, 18 26-30 selectivity to trons-decalin, 18 24, 25 olefin intermediates, 18 30-45 dihydro-and hexahydronaphthalenes, 18 32, 33 analysis of products, 18 33 oc-tahydronaphthalenes, 18 34-45 analysis of products, 18 34 deu-... 

The formation of 1,9- and cis-1,2-octalin from ci5,cis-l-decalol is a clear indication of the dehydration by means of a trana elimination reaction ... 

The dehydration of cis,alumina surfaces, could readily explain the observed data ... 

The formation of 1,9-octalin from fraras,[Pg.65]

Similarly Smith and Burwell (61) concluded that desorbed -octalin is a common intermediate in the formation of cis- and hydrogen-deficient species, possibly an allyl-77- complex (see Section III,C). 

Direct calorimetric measurements of two ozonides have been reported. Both the enthalpy of combustion of the ozonides and the direct enthalpies of ozonation of the precursor olefin were measured. The first species to be studied was the purported ozonide of A °octalin (l,2,3,4,5,6,7,8-octahydronaphthalene) . It is doubtful that the product of the octalin ozonation reaction would be the molozonide formed by direct addition with no subsequent rearrangement (i.e. ll,12,13-trioxabicyclo[4.4.3]tridecane) but perhaps even less likely is the rearranged and hence normal ozonide, the ll,12,13-trioxa[4.4.2.1]paddlane. From the published enthalpy of combustion of —5628 kJmoU, we derive an enthalpy of formation of this species, whatever it is, of —593.7 kJmoU. ... 

Fig (19) Octalin ketal (163) is converted to kete dithioacetal (164) by the cleavage of ketal function and condensation with carbon disulfide and methyl iodide. Subjection of (164) to the action of dimethylsulfonium niethylide and acid hydrolysis leads to the formation of unsaturated lactone (165).lts furan silyl ether derivative is caused to undergo Diets-Atder reaction with methyl acrylate to obtain salicyctic ester (166) which is converted by standard organic reactions toabietane ether (167). It is converted to aiiylic alcohol (168) by epoxidation and elimination. Alcohol (169) obtained from (168) yields orthoamide which undergoes transformation to amide (170). Its conversion to the previously reported intermediate has been achieved by epoxidation, elimination and hydrolysis. 

Formation of an enamine radical cation 45 was proposed as the chain initiation step in the autooxidation of enamines and SchifFs bases of a,/ -unsaturated ketones to give unsaturated 1,4-diones37. Pyrrolidine enamine of 10-methyl-A1(9)-octal-2-one (44) reacts with oxygen at room temperature to produce, after acid hydrolysis, 10-methyl-A1 (9)-octalin-2,8-dione (47) in 20% yield. Addition of a catalytic amount of FeCl3, Cu(OAc)2 or CuCl2 causes a pronounced enhancement in the oxidation rate and increases the yield to 80-85% after 1 h. 

IntrodnclUm offkHctionmlized oagmlar methyl groups. The reaction of ethyl vinyl ether with 10-methyl-A -2-octalol (1) catalyzed 1 mercuric acetate in a sealed Carius tube for 12 hr. at 200° gives 9-formylmethyl-10-methyNA -octalin (2, 85% yield) together with some dienes (3,15 % yield). Use of phosphoric acid leads only to the dienes (3). The one-step procedure involves formation of the vinyl ether followed by Claisen... 

The stereochemistry of hydrogenating naphthalene is described in Weitkamp s review. Mainly cis-decalin is formed when the hydrogenation is catalyzed by platinum metals under relatively mild conditions ruthenium is the most stereoselective (95-98% cis) while palladium is the least. The t/ans-decalin which is formed appears to result from the reduction of octalin intermediates via a mechanism similar to that which accounts for the formation of frans-dialkylcyclohexanes from dialkylbenzenes. 

Solutions of Group I metals in the lower molecular weight amines are more potent reductants than those in liquid ammonia, and as a general rule substrates are more extensively reduced than by the Birch method. o Naphthalene (49 Scheme 48), for example, is reduced by a solution of lithium in ethylamine to a 1 1 mixture of A W- and A -octalins (214) and (215). If ethylenediamine is employed as the medium, the completely saturated decahydronaphthalene is formed, while the proportion of (215) may be increased to 80% by utilizing a (1 1) mixture of ethylamine with dimethylamine. The formation of the more-substituted alkene appears to be a general result for such primary and secondary amine mixtures and has been used to good effect in the reduction of both toluene and cumene to their 3,4,5,6-tetrahydro derivatives (216) and (217), respectively, in ca. 80% yields. A comprehensive review of these kinds of reducing systems, which also draws comparisons with the Birch method, is available,but more recent-... 

Preferential formation of diaxial products is further illustrated by the reaction of the octalin (octahydronaphthalene) depicted below with an aqueous solution of bromine. Addition of the electrophilic Br to the less hindered a-face of the double bond and antiperiplanar, antiparallel opening of the resultant bromonium ion intermediate by HO" furnishes the diaxial bromohydrin. 

If opportunity is given, a (thiolated) carbon atom can be transferred from a sulfur ylide to a double bond with diastereocontrol. The carbon remains on that side of the molecule which contained the sulfur initially e.g. equation 40). By similar chirality transfer, the (3-oriented phenylthio group of octalin (147) determines the -orientation of the transposed PhSCH2 unit in the reaction product (148 equation 41). The efficient formation of a quaternary center from (147) is all the more remarkable since an... 

On rhodium the intermediate seems to be preferentially cis adsorbed, and on palladium it may be largely trans adsorbed. The amount of exchange is slightly more in the ois-adsorbed state because the bridgehead hydrogen is toward the catalyst. Thus, the deuterium content was higher in the cis-decalin than in the frons-deoalin. Presumably, the isomerized octalin is formed only from the cis-adsorbed state in competition with formation of cia-decalin. 

Actually, rhodium and iridium can be used as well as ruthenium in mixtures with palladium. The results, however, allow only the qualitative statement that olefins are significant intermediates. The presence of more than one olefin isomer and uncertainty of the precise ratios of formation and rates of migration preclude any quantitative estimate. The experiments with mixed catalysts were terminated after 20 to 50% conversion. The mixed catalysts not only gave higher yields of (raws-decalin but the actual concentrations of the octalins present in the reaction mixture were lowered owing to preferential adsorption on the palladium component. 

Fio. 14. Road map showing the role of tetralins and octalins in the formation of the various 2-methyldeoalin stereoisomers 1000 psig hydrogen pressure, 100°, 0.6% Ru/AlsOa catalyst. 

The two structures with/sue gauche interactions, isomers 6 and 7, are distinguished on the basis that the high yield of isomer 6 reflects formation from a tetralin intermediate or from a pair of octalin intermediates, one of which is relatively unhindered, whereas the direct routes to isomer 7 are both via proper but badly hindered octalin intermediates ... 

Structures 5 and 6 differ by one gauche interaction but the difference is nearly compensated by the doubling of the equilibrium yield by the existence of isomer 6 as a dl pair. Distinction is made by the formation of isomer 6 via the tetralin intermediate. The yield is second highest in the system because the tetralin is adsorbed on its hindered side although with the methyl group remote from the aromatic ring, neither side is badly hindered. The kinetic yield of isomer 5 is low because the octalin intermediate is badly hindered ... 

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