Trans-Octalin

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) ... 

With octalin (55), rotation to the trans chair form (59) followed by protonation from the outside face of the double bond at the less substituted carbon atom leads to the tertiary cation (60) with net equatorial introduction of the proton. Rotation to a trans boat form would lead to net axial protonation<84) ... 

The reduction of A9(10)-octalin to cis- and /ran.v-decalins occurs with cis to trans stereoselectivities that vary with the nature of the organosilicon hydride employed. The ratios are 0.28-0.59 with n-butylsilane, 0.67 with diethylsilane,204 0.34212 or 0.72204 with triethylsilane, 0.67 with diphenylsilane, 0.77 with diphen-ylmethylsilane,212 1.3 8204—1.80127,212 with triphenylsilane, 0.54 with triisopen-tylsilane, 1.17 with tricyclopentylsilane, 2.57 with tri-.vcc-bulylsilane, 3.35 with di-ferf-butylsilane, 4.88 with di-ferf-butylmethylsilane, and 13.3 with tri-rm-butylsilane.204 Opinions differ about the mechanistic significance of these changes in isomer ratios.204,212... 

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. 

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-... 

In a study of the addition of nitrosyl chloride or nitrosyl bromide to norbor-nene and norbomadiene, it was observed that (a) there was no structural rearrangement during the reaction, (b) a cis addition had taken place, (c) nucleophilic solvents such as ethanol or acetic acid were not incorporated in the products. These facts seem to speak against an ionic addition mechanism, while a free radical initiated by NO radicals was considered unlikely since nitric oxide is inactive toward norbomadiene. Therefore a four-center mechanism has been suggested [70], However, when a relatively simple, unstrained olefin such as A9-octalin was subjected to the reaction, only blue, crystalline, monomeric 9-nitroso-10-chlorodecalin was produced. This product had a trans configuration. Thus it is evident that the structure of the olefin has a significant bearing on the steric course of the addition [71]. 

The nearly equal amount of cis and trans products formed from 1,5-dimethylcyclo-hexene is explained by the almost equal degree of hindrance of the homoallylic methyl group with the catalyst surface in the alternate adsorption modes.63 64 Another interesting example is the platinum-catalyzed hydrogenation of isomeric octalins.65-67 If syn addition to the double bond is assumed, in principle, both cis- and mms-decalin are expected to result from l(9)-octalin, but only the cis isomer from 9(10)-octalin. In contrast with these expectations, the isomers are produced in nearly the same ratio from both compounds. Transformation in the presence of deuterium revealed that most of the products contained three deuterium atoms. This was interpreted to prove that the very slow rate of hydrogenation of 9(10)-octalin [Eq. (11.9)] permits its isomerization to the 1(9) isomer. As a result, most of the products are formed through l(9)-octalin [Eq. (11.10)] ... 

Good selectivities for m-decalin are exhibited by all platinum metals except palladium that is unique in the high yield (52%) of trans-decalin 66,67 It was proved that isomeric octalins are involved in determining product selectivities66,67 (see Section 11.1.2). 

In order to obtain the trans-fused octalin, the cis-fused octaline 423 was oxidized with chromium trioxide in acetic acid to yield the ketone 424. The latter was treated with bromine in acetic acid to produce the a-bromoketone 425 in a yield of 98%. Dehydrobromination of 425 with. /V-phenylbenz-amidine afforded the a/i-unsaturated ketone 426 in 90-95% yield. The... 

A series of angular-substituted octalins 84 and 85 were studied using electron-impact mass spectroscopy.86 It was found that the major fragmentation pathway of the derivatives 84 having a trans relationship between the silyl substituent and the angular substituent involved loss of the angular substituent... 

C11H14N2 trans-2 amino-5-methyl 4-phenyl-1-pyrroline 50901-87-6 400.35 34.398 1,2 22146 C11H1402 9-methyl-d-5(10)-octaline-1,6-dione 20007-72-1 480.16 41.981 2... 

But we have noticed, in several instances, that small amounts of naphthalene arc found in the products of acid-catalyzed conversion of terpenes (unpublished results), a fact nicely explained by hydrogen tran.sfer from the octalin. 

In a later paper Meinwald concluded that nitrosyl chloride adds cis to strained double bonds, such as that in norbornene, but that it adds trans to unstrained olefins (A -octalin). In accordance with this view of the addition is a report by Hassner on the reaction of cholesteryl acetate (4). Nitrosyl chloride was passed into methylene chloride or carbon tetrachloride until a deep burgundy color developed, the steroid... 

Saturation seems rather to be a two-center process, and a mechanism whereby the double bond of A AO-octalin isomerizes before any trans-decalin is formed seems better to explain these results. 

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. 

Another observation that is difficult to reconcile with a mechanism of topside addition from adsorbed molecular hydrogen is the uniquely high yields of trans isomers obtained with palladium catalysts, i.e., about 85% frana-decalin from either Ai- -octalin or A i -octalin. Palladium, of all the transition metals, is the one deemed most likely to dissociate adsorbed hydrogen, and therefore least likely to involve molecular hydrogen in the saturation mechanism. On the other hand, palladium is one of the most effective transition metals for olefin isomerization and could isomerize A > -octalin to the thermodynamically unpreferred but rapidly saturating A > -octalin. 

Examination of the molecular model of A >i -octalin reveals that it can exist in three distinct chair-chair conformations. One modification is a meso form with a plane of symmetry such that one ring is the mirror image of the other it has one twofold axis of symmetry, i.e., a = 2. The other two chair-chair conformations are a dl pair each enantiomer has three twofold axes of symmetry, i.e., v = 4. The chair conformation of Ai> -octalin is a dl pair with no twofold axis of symmetry, i.e., a=l. The chair conformation of chair conformation of trans-Ai.2-octalin is a dl pair with no twofold axis of symmetry, i.e., a=l. These parameters and the differences in conformational energy based on them are collected in Table XXXVIII. 

---