Decalin formation

Fig. 10. Steric factors governing frans-decalin formation...

The catalysts were tested in isoprene, benzene and naphthalene hydrogenation reactions. The catalysts prepared by oxidation of the intermetallic at 703 K were found to be more active than those oxidized at room temperature. In isoprene hydrogenation the catalyst based on mischmetal has a larger activity than the other alloys and is comparable to the catalysts prepared by other routes. In benzene hydrogenation the Ni and Ce based catalysts prepared by coprecipitation were found the most active. In naphthalene hydrogenation the fully oxidized intermetallics are four times more active than the partially oxidized ones. In addition they are independent of hydrogen pressure and selective into decaline formation. 

Various bicyclic and polycyclic compounds are produced by intramolecular reactions] 127]. In the syntheses of the decalin systems 157 [38] and 158 [128], cis ring Junctions are selectively generated. In the formation of 158, allyhc silyl ether remains intact. A bridged bicyclo[3.3. l]nonane ring 159 was constructed... 

The same regioselective and stereospecific reactions are observed in decalin systems. The 3/3-formate 605 is converted into the a-oriented (j-allylpalladium complex 606, and the hydride transfer generates the fra .s-decalin 607, while the cis junction in 610 is generated from the 3tt-formate 608 by attack of the hydride from the /3-side (609). An active catalyst for the reaction is prepared by mixing Pd(OAc)2 and BU3P in a 1 I ratio with this catalyst the reaction proceeds at room temperature. The reaction proceeded in boiling dioxane when a catalyst prepared from Pd(OAc)2 and BujP in a 1 4 ratio was used[390]. 

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

It was also suggested that the relationship of the two forms (A) and (B) might be that of stereoisomerides of the cis-trans decalin type and a good deal of work was done to provide experimental evidence for this view or the alternative that they are structural isomerides. It was also found that of the methods used to synthesise the pyridocoline system all but one gave norlupinane (A) on reduetion, the exceptional formation of uorlupinane (B) being limited to reduction of the 1-keto compound by the Clemmensen method. 

Appropriate choice of catalyst permitted formation of either of two dihydro derivatives of mevinolin in high yield (67). Hydrogenation of mevinolin over platinum oxide in ethyl acetate gave the tetrahydro derivative as a 1 3 mixture of CIS- and rrd 5-decalin isomers. 

Similarly, efficient tetracyclization (MeAlCl2-promoted) of the bis-allylic silane/ bis-epoxide 97 constitutes the key step in the synthesis of (+)-a-onocerin. In this case, because of the presence of the bis-allylic silane group, a double bis-annula-tion occurs, with the formation of the ethylene-bridge linked bis-decalin system present in the target compound (Scheme 8.26) [46],... 

Lastly, we isolated a tetrabromo compound 21 (ref. 10) which is derived from solvent. IH and NMR spectra of 21 indicates the formation of a highly symmetrical compound whose configuration is not known. Possible configurations are given on scheme 10. On an independent reaction we treated decalin with bromine at high temperature and obtained 21 in high yield. 

The formation of the naphthalene (73) from the bis-ylide (72) and diethyl ketomalonate involves an unusual olefin synthesis on the carbonyl of an ester group. The methylene-pyrans (75) were formed when the diethyl malonates (74) were refluxed with j3-keto-ylides in xylene or decalin. Possible intermediates are the ketens (76) and the allenes (77). Addition of ylide to the allenes gives the betaines (78) which form methylene-pyrans either directly or via acetylenes as shown. 

Entry 6 shows a stereoselective formation of a highly substituted frans-decalin system. The reaction in Entry 7 establishes a taxanelike structure. The stereochemistry is consistent with a TS in which both the carbonyl oxygen and the methoxy group are coordinated to aluminum. 

ROP. Their concentration is lower than the one of Ethyl- and Propyl-ROP at low conversions, but with increasing conversion they become the most abundant ROP group. Nevertheless, a noteworthy trend is observed for concentrations of all ROP groups, except Butyl-ROP, which increase rapidly after reaching conversion higher than 60%. This links the ROP formation to the secondary formed skeletal isomers of decalin (DMBCO) rather than to MBCN, which are present already at lower conversions in sufficient amounts. 

Mechanisms of the formation of the decal ins in the recovered solvent were based on their isotopic contents. The cis-Decalin-die had a greater protium content than the recovered Tetralin-di2-This suggested that hydrogen transfer from the coal to the tetralin is involved in the formation of cis-Decalin. 

The isotopic composition of the Decal ins in the spent solvents is indicative of the mechanisms of their formation. A total of 6 hydrogen atoms are added to the Tetralin to form Decal in. In E10, during the course of the experiment, the average protium concentration in the Tetralin increased from 2.3 to 21.3 atom % 1H. The protium content of 34 atom % 1H in the cis-Decalin was greater than the protium content in the Tetralin. Likewise in El9, the protium content in the Tetralin increased from 1.0 to 12.3 atom% H, while the cis contained 18.8 atom % 1H. This increase of pro-... 

An investigation of the isotopic composition of the Decal ins, which were formed as minor products in the donor solvent experiments, showed that cis-Decalin was formed preferentially. Its formation and its increased protiurn incorporation may have resulted from increased contact with the coal surface. Trans-Decal in contained less protiurn than the Tetralin, which suggests that most of the trans-Decalin was formed with deuterium from the Tetralin-di2 and deuterium gas. 

Intramolecular Diels-Alder cyclizations of (E)- -nitro-1,7.9-decatrienes under thermal conditions and Lewis acid conditions lead to the formation of decalin ring systems with excellent endo selectivity (Eq. 8.21). This strategy is used for preparing of the AB ring system of norzoanthamine.33... 

In the present estimation, a continuous dehydrogenation reactor in which decalin is supplied to the catalyst at various feed rates without internal refluxing is assumed. Here all the condensable products and unconverted decalin were removed from the reactor to the condensation part (see Figure 13.22). Now, the stationary rates of hydrogen generation (VH), naphthalene formation (VN), and evaporation of unconverted decalin (VD) are defined as the magnitudes per area of the catalyst layer (mol/m2h). All these rates are expressed from mass balance as follows . 

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