Tricyclo 3.3.1.0 octenes

The purported exo-addition of 3,3-difIuoro-l,2-di(trifluoromethyl)cyclopropene to cyclopentadiene has been re-examined, and by using the n.m.r. data of (103)—(105) the major product has been reassigned as the corresponding e/uio-tricyclo-octene. A further claim to [2 + 4] exo-addition of cyclopropene has been made from the reaction between 1,3,3-trimethylcyclopropene and isobenzofuran. Further details on the reaction of cyclopropenes with thiophen 1,1-dioxides to give isomerically pure cycloheptatrienes have appeared. ... 

Recently a reverse perturbation effect of a cyclopropyl group on facial selectivities was described in two bicyclic systems, bicyclo[2.2.2]octane 59 and norbomane (bicyclo[2.2.1]heptane) 60 [124]. Bicyclo[2.2.2]octene 59a, annulated with an exo-cyclopropyl group, i.e., exo-tricyclo[3.2.2.0 ]non-6-ene, and 7-methylenenor-bomane 60a, annulated with an exo-cyclopropyl group, i.e., 8-... 

Another option is the twofold Michael addition/SN-type sequence of which manifold versions have been published. Thus, Padwa s group reported on the di-astereoselective synthesis of bicydo[3.3.0]octenes [199], while in another approach by Hagiwara and coworkers various tricyclo[3.2.1.0]octane derivatives and similar bridged compounds have been constructed [200]. The group of Spitzner has also been engaged intensively in Michael/Michael/SN-type processes [201]. One such ex-... 

Other examples of the synthesis of cyclobutanes with abstraction of an allylic hydrogen are the photochemical formation of tricyclo[4.1.0.03,7]heptan-5-ones (e.g., 5) from norborn-5-en-2-ones33 and of bicyclo[4.2.0]octenes (e.g., 7) from doubly unsaturated ketones.34... 

Cycloadditionen von Olefinen an Benzol gelangen Wilzbach und Kaplan (328). Beim Bestrahlen etwa 10-proz. Losungen von cis-Buten-(2), Cyclopenten und 2,3-Dimethylbuten-(2) in Benzol bilden sich 6,7-substituierte Tricyclo[3,3,0,02.8]octene-(3) (Formel 132), die durch Addition des Olefins an Benzvalen (Formel 133) unter Offnen eines Drei-ringes formuliert werden konnen (vgl. Kap. 3.4.). 

Cycloocta-l,5-diens (Formel 41) in der Gasphase. Neben polymerem Material entstehen zu 2—3 % zwei isomere Substanzen, die als Bicyclo-[5,l,0]octen-(3) (Formel 42) und Tricyclo[3,3,0,02< ]octan (Formel 43) identifiziert werden konnten (280, 283). 

Erwahnt sei femer die photochemische Isomerisierung des exo-Tricyclo-[3,2,l,08 4]octen-Derivates 48 zum Tetracyclo[3,3,0,02 8,04>8]octan-Deri-vat 49 (216), obwohl diese Reaktionen im strengen Sinne keine Cyclo-merisation darstellt. Auf analoge Weise ist auch das unsubstituierte Tetracyclo-octan sowohl aus exo- als auch aus endo-Tricyclo [3,2,1,02.4]-octen-(6) zuganglich (125). 

W. Eberbach u. G. von Veh Photochemische Isomerisierung des Tricyclo [3.2.1.02 4]octen-Systems, eines Homo-vinylcyclopropan-Sy-stems. Angew. Chem. 77, 454 (1965). 

Bromination of alkyIcyclopropanes can result in extensive rearrangement bromi-nation of n-butylcyclo pro pane (79) in the dark and in the presence of N-bromosuccinimide to trap any HBr produced, results in a mixture of 1,2-, 1,3-, 1,4-, 1,5- and 1,6- dibromides (Scheme 19). Rearrangement can also be induced by proton acids, for example, endo-tricyclo[3.2.1.0 ]octene (80) reacts with acetic acid to give 3-acetoxybicyclo[3.2.1]oct-l-enes (81) (Scheme 19) and Djerassi and coworkers have recently reported reaction of... 

In the presence of CuCl, exo-3-tricyclo[3.2.1.02 4]octene-6-yl-3-hexene-2-oic acid methyl ester (72) is isolated after TLC in 60% yield (Z E = 1.5 1) 67c). This is comparable to the course of the cyclopropanation of norbornadiene with both the Simmons-Smith reagent and diazomethane-CuCl. In both cases the exo-anti route is favored over the exo-syn 63). It is important to notice, that in the above mentioned nickel(O) catalyzed reactions (Eq. 11) hexatriene derivatives have never been observed. 

Bicyclo[2.2.2]octen-2-ones 25 afford tricyclo[3.3.0.0 ]octan-3-ones 26 in very good to excellent yields. Quantum yields for these conversions are in the range 0.5-1.0. The products have been used as building blocks in the synthesis of polycyclopentanoid terpenes and prostacyclin ana-logues. 2" - "... 

Molecules containing a bicyclo[2.2.2]octen-2-one subunit fused or bridged to an additional ring have been investigated in detail, as their oxa-7c-methane rearrangements afford tetracyclic ketones, usually in very good yields. The commonest examples are 7,8-fused substrates 33 which afford 6,7-exo-fused tricyclo[3.3.0.0 ]octan-3-ones 34. 

Tricyclo[3.3.1.03 6]non-7-en-2-ones (43, X = CH2), tricyclo[4.3.1.03-7]dec-8-en-2-ones (43, X = CH2CH2), and tricyclo[5.3.1.03,8]undec-9-en-2-ones (43, X = CH2CH2CH2) and other 3,8-bridged bicyclo[2.2.2]octen-2-ones rearrange in good to excellent yields to 4,6-bridged tricyclo[3.3.0,02,8]octan-3-ones (44) upon irradiation in acetone in the presence of acetophenone.149,170... 

Valence tautomerizfttion. Tris(triphenylphosphine)chlororhodium (in the absence of hydrogen) catalyzes valence tautomerization.6 Thus, when exo-tricyclo[3.2.1.02-4]octene (1) is warmed at 90° with 1.3 moles % of the catalyst it is converted into a mixture of (2, 62%), (3, 32%), and (4, 6%). Rhodium on carbon... 

Sehr gute Uberlappungsvoraussetzungen bietet exo-Tricyclo[3.2.1.0s 4]octen-(6) (I It =H). In Ather wird bei Bestrahlung (450 W Hanovia Quecksilber-Mitteldruek-Lampe) Tetracyclo [3.3.0.02-s.0i>e]octan (II R ==H) mit 29%iger Ausbeute gebildet7 ... 

Entsprechend entsteht aus 4-Oxo-4H-chromen und Cyclopenten 8-Oxo-(benzo-3-oxa-tricyclo[6.3.0.02 ]undecen-(4)y 3. MitButin- (2) wird 7-Oxo-9,10-dimethyl-(3,4-benzo-2-oxa-bicyclo[4.2.0]ocladien-(3,7)y gcbildet1.2. und mit 1,1-Dimetkoxy-athylen ergibt sich 10,10-Dimethoxy-7-oxo-(benzo-2-oxa-bicyclo [4.2.0] ocfen-(J)) und 3,3-Dimethoxy-oxetan-(2-spiro-7y- 10,10-dime,lhoxy-(ljfMzo-2-oxa-bicyclo[4.2.0 octen-(3)y2>3. 

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