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Decalin transformations

Fig. 8.11 Decalin transformations on metal -modified zeolites A) Reaction scheme and B) chemical structures of the starting material and representative components of the main modeled lumps decalin (D), 2-D skeletal isomers of decalin (2-D), 3-D skeletal isomers of decalin (3-D), ring opening products (ROPs) and cracking products (CPs). (Reprinted with permission from M. Kangas, D. Kubicka, T Salmi, D.Yu. Murzin, Reaction routes in selective ring opening of napthenes. Top. Catal. 53 (2010) 1172—1175. Copyright 2010 Springer). Fig. 8.11 Decalin transformations on metal -modified zeolites A) Reaction scheme and B) chemical structures of the starting material and representative components of the main modeled lumps decalin (D), 2-D skeletal isomers of decalin (2-D), 3-D skeletal isomers of decalin (3-D), ring opening products (ROPs) and cracking products (CPs). (Reprinted with permission from M. Kangas, D. Kubicka, T Salmi, D.Yu. Murzin, Reaction routes in selective ring opening of napthenes. Top. Catal. 53 (2010) 1172—1175. Copyright 2010 Springer).
The electrophilic cyclizations of trans, rra .y-l,5-cyclodecadienes has been extensively investigated, principally with germacrane-type sesquiterpenes (121), but also with model substrates (122). Electrophiles effect regiospecific addition to the 1,2-double bond and stereospecific cyclization to /ran -decalins, transformations closely parallel to the biogenesis of the eudesmanes (725). Similar cyclizations have been observed with numerous oxygenated germacrane derivatives (727). [Pg.102]

In a series of publications over the past few years, the group of Barriault has reported on microwave-assisted tandem oxy-Cope/Claisen/ene and closely related reactions [175-178], These pericyclic transformations typically proceed in a highly stereoselective fashion and can be exploited for the synthesis of complex natural products possessing decalin skeletons, such as the abietane diterpene wiedamannic... [Pg.165]

As is evident from Figure 13.25a, the area loading of decalin is closely related with the stationary conversion. Because the highest conversion was attained at around the area loading of 70 (L/m2h) (= 4.48 X 102 (mol/m2h)) with the catalyst in the superheated liquid-film state, Equation 13.8 is transformed in to Equation 13.9, giving a reciprocal correlation curve between the one-pass conversion (A) and the reaction area needed to a 50 kW power (S) (Figure 13.25b). [Pg.461]

Corey s retrosynthetic concept (Scheme 9) is based on two key transformations a cationic cyclization and an intramolecular Diels-Alder (IMDA) reaction. Thus, cationic cychzation of diene 50 would give a precursor 49 for epf-pseudo-pteroxazole (48), which could be converted into 49 via nitration and oxazole formation. Compound 50 would be obtained by deamination of compound 51 and subsequent Wittig chain elongation. A stereocontroUed IMDA reaction of quinone imide 52 would dehver the decaline core of 51. IMDA precursor 52 should be accessible by amide couphng of diene acid 54 and aminophenol 53 followed by oxidative generation of the quinone imide 52 [28]. [Pg.21]

Therefore, nine steps or synthetic operations are necessary in the conessine synthesis for isomerising the cir-B/C decalin system to trans-hIC, a transformation that in the cortisone synthesis is accomplished without any extra step, since it takes place spontaneously in the oxidation step, which, in turn, is necessary to introduce the second angular methyl group and build up ring D of cortisone in a stereoselective manner. Better correlation amongst different synthetic operations would be difficult to find in more recent synthesis of similar complexity and magnitude than that of Sarett. [Pg.24]

Bhattacharyya et al. reported the first total synthesis of clausenalene (90) to establish its structure (99). This total synthesis uses Japp-Klingemann and Fischer-Borsche reactions as key steps. The phenyl hydrazone 1000 required for the transformation to 1-0x0-tetrahydrocarbazole 1001 under Fischer-Borsche conditions was obtained by condensation of 2-hydroxymethylene-5-methylcyclohexanone (999) with diazotized 3,4-methylenedioxyaniline (998) using Japp-Klingemann conditions. Wolff-Kishner reduction of 1001 furnished 3-methyl-6,7-methylenedioxy-l,2,3,4-tetrahydrocarbazole (1002), which, on aromatization wifh 10% Pd/C in decalin, afforded clausenalene (90) (99) (Scheme 5.143). [Pg.283]

This electrophilic substitution is unique among chemical transformations, in the sense that a reaction takes place on a completely deactivated site difficult to access by other reactions. With fluorine as a reagent, decalins, bicyclohexyls, alkylcycloalkane derivatives 6-8 and many more can be fluorinated at their tertiary position and subsequently dehydrofluorinated.37... [Pg.172]

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)] ... [Pg.625]

Similarly, the zirconocene system transforms perfluorinated Decalin to perfluoronaphthalene and its 2//-derivative (15)159 at room temperature. When the starting mixture is reacted for 14 h, the dominant organic product is 2//,6//-hexafluoronaphthalene (16), formed by subsequent reduction of 15. Deuterium incorporation in 15 and 16 from tetrahydrofuran-r/8 demonstrates that the solvent is a hydrogen source.159... [Pg.311]

The Diels-Alder condensation of p-benzoquinone with vinylacrylic acid gives a cis decalin adduct (XXXIV), which is a prerequisite for the desired DE ring junction of the reserpine molecule. This cis configuration is preserved by proper choice of reagents, and in only one single instance has a transformation into a trans decalin been reported (186). In his modified route, Woodward has used methyl acrylate instead of the free acid, and others have used the corresponding ethyl or isopropyl esters (187, 186). [Pg.318]


See other pages where Decalin transformations is mentioned: [Pg.323]    [Pg.323]    [Pg.22]    [Pg.965]    [Pg.169]    [Pg.56]    [Pg.576]    [Pg.785]    [Pg.2]    [Pg.1187]    [Pg.284]    [Pg.170]    [Pg.424]    [Pg.650]    [Pg.39]    [Pg.221]    [Pg.226]    [Pg.228]    [Pg.325]    [Pg.4]    [Pg.156]    [Pg.86]    [Pg.21]    [Pg.263]    [Pg.248]    [Pg.405]    [Pg.16]    [Pg.197]    [Pg.358]    [Pg.37]    [Pg.672]    [Pg.291]    [Pg.284]    [Pg.215]    [Pg.631]    [Pg.103]    [Pg.668]   
See also in sourсe #XX -- [ Pg.461 , Pg.461 ]




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