Tricyclo octane derivatives

Fig. 23.6 Four isomeric tricyclo-octane derivatives showing extremely pronounced effects of stereochemistry on chemical shift values (see Fig. 23.7).

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-... 

In contrast to norbornadiene, bicyclo[2.2.2]octa-2,5-diene does not always give the transan-nularly bridged products in normal solution reactions, whereas in the anodic electrooxidation this nonconjugated octadiene showed the formation of products, mainly tricyclo-[2.2.2.0 ]octane derivatives 5 and 6 from transannular interaction, exclusively. ... 

The tricyclo[3.3.0.0 ]octane system usually undergoes ring opening to give bicyclo[3.3.0]octane derivatives by cleavage of the C2-C8 bond when treated with lithium in liquid ammonia. In the case of tricyclo[3.3.0.0 ]octan-3-one (31, R = = H), a small amount (5%) of the... 

Haywood-Farmer, J. S., Pincock, R. E. (1969). Synthesis and solvolytic reactivity of 8-tricyclo[3.2.1.0]octane derivatives. Journal of the American Chemical Society, 9/(11), 3020-3028. 

Gold(I) catalysis has been reported to convert cyclopentenes to cyclohexadienes and involves ring expansion and a [l,2]-alkynyl shift. It is thought to be initiated by the cleavage of the bridging C-C bond and the proposed allyl-gold cation intermediate is trapped with alcohol to give bicyclo[3.2.1]octadiene and tricyclo[3.2.1.0 ]octane derivatives (Scheme 110). ° ... 

Oxabicyclo[3.2.0]heptanes are also produced in the CuOTf-catalyzed photocycloadditions of allyl 2,4-hexadienyl ethers (eq 24). The CuOTf-catalyzed photocycloadditions of bis-2,4-hexadienyl ethers are more complex. Thus UV irradiation of 5,5 -oxybis[( )-l,3-pentadiene] in THF for 120 h produces vinylcy-clohexene and tricyclo[3.3.0.0 ]octane derivatives (eq 25). However, shorter irradiations reveal that these products arise by secondary CuOTf-catalyzed rearrangements of 6,7-divinyl-3-oxabicyclo[3.2.0]heptanes that are the primary photoproducts (eq 26). UV irradiation of the divinylcyclobutane intermediates in the presence of CuOTf promotes formal [1,3]- and [3,3]-sigmatropic rearrangements to produce a vinylcyclohexene and a 1,5-cyclooctadiene that is the immediate precursor of the tricyclo[3.3.0.0 ]octane. 

Bkycloheptane and Bicyclo-octane Derivatives.—Room temperature addition of diphenyldiazomethane to 7-t-butoxynorbornadiene yielded all of the possible 1,3-dipolar cycloaddition products (exo rule not obeyed). Pyrolysis of these adducts effects entry to the 3,3-diphenyltricyclo[3,2,l,0 ]octane system e.g. (852) is thus obtained. Procedures for the preparation of tricyclo[3,2,l,0 ]oct-6-ene-3-carboxylic acids, e.g. (853), essentially isomer-free have been described. Reductive dechlorination of (854), the Diels-Alder product of addition of 3,3-dimethylcyclo-propene to tetrachlorocyclopentadienone dimethyl acetal, followed by acetal hydrolysis and cheletropic loss of CO has been used to prepare 7,7-dimethylcyclohepta-triene. °... 

Before the explanation of ladder poly silanes is started, ladder compounds of other Group 14 elements are briefly mentioned. Hydrocarbons with a ladder-shaped carbon framework are known as ladderanes. The study on ladderanes goes back to 1927, when bicyclo[2.2.0]hexane ([2]ladderane) was synthesized by the reduction of dy-l,4-dibromocyclohexane with sodium.19 Ladderanes so far reported are tricyclo[4.2.0.02,5]octane ([3]ladderane),20 tetracyclo[4.4.0.02,507,1°]decane21 ([4]ladderane), and a number of their derivatives (Fig. 3). 

The thermolysis of ladderanes has been studied in detail (Scheme 1). On heating, bicyclo[2.2.0]hexane and its derivatives exhibit skeletal inversion and cleavage to 1,5-hexadiene derivatives.26 The thermolysis of anti- and yyft-tricyclo[4.2.0.02,5]octanes and their derivatives gives cis,cis- and cis, trans-1,5-cyclooctadienes, cis- and trans-1,2-divinylcy clobutanes, and 4-vinylcyclohexene as ring-opening products.27-29 Furthermore, syn-tricyclo-[4.2.0.02,5]octane isomerizes to aw//-tricyclo[4.2.0.02,5]octane.29c,d The thermodynamic parameters and the reaction mechanisms for these thermal reactions have been discussed. 

A detailed comparison of the rearrangement of 1,3-radicai cations and carbocations derived from tricyclo [3.3.0.0 " ] octanes has shown (by eiectron-transfer oxidation and protonation, respectiveiy) that electronic substituent effects on the diyi sites profoundly influence the regioseiectivities of the Wagner-Meerwein 1,2-shifts. The... 

The Michael addition followed by Intramolecular Ring Closure (MIRC) reactions have been recognized as a general synthetic approach to carbocyclic three-membered ring derivatives [1]. The enhanced Michael reactivity of methyl 2-chloro-2-cyclopropylideneacetate (1-Me) towards thiolates, alkoxides, lithiated amides and cyclohexadienolates (see below) allows one to perform highly efficient assemblies of spiropentane, tricyclo [3.2.1.0 ]octane, bicyclo [2.2.2] octane... 

The Cj - and 54-symmetric tetraesters of tricyclo[3.3.0.0 ]octane (430 and 431) have been prepared by oxidation of diene 429 To access the parent hydrocarbon (435), acid chloride 432 was transformed to the derived ketene which undergoes intramolecular [2+2] cycloaddition The resulting cyclobutanone (433) serves as precursor to perester 434 whose thermal decomposition proceeds with chain transfer in competition with cleavage The unique arrangement of the carbon atoms in 435 is such that the smallest rings are all five-membered. The highly symmetric structure may be viewed as a constrained cisoid bicyclo[3.3.0]octane (as well as the symbol of NATO). 

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). 

The reduction of a series of bicyclic and tricyclic ketoximes using both Na-ethanol and LAH has been carried out and the product mixtures analyzed in detail. In this investigation it was found that reduction of the oximes derived from two tricyclo[2.2.1.0 ]heptan-3-ones (87) and (88) with either LAH-THF or Na-ethanol gave mixtures of exo (89) and (90) and endo (91) and (92) amines. Neither method of reduction was particularly stereoselective and the yields were somewhat better with LAH (87 76% versus 67% and 88 67% versus 44%). In contrast, reduction of the oximes of three bicyclo[2.2. l]heptan-2-ones (93)-(95) with LAH-THF gave significant quantities of azabicyclo[3.2.1]octanes (96)-(98) in addition... 

As an alternative to a radical chain mechanism for this bromination, a cationic mechanism has been proposed for the reaction between 48 and A-bromosuccinimide. It involves attack of bromine at C6 of 48 leading ultimately to the cyclopropylmethyl cation A. This cation is a bromo derivative of tricyclic cyclopropylmethyl cation, which has been shown to be the common intermediate in the solvolysis of esters of tricyclo[3.2.1.0 ]octan-3-ol, endo- and exo-tricyclo[3.2.1.0 ]octan-4-ol and of cxo-bicyclo[3.2.1]oct-2-en-7-ol. It has been shown that under long-lived ion conditions at — 78 C such cations are the most stable species that are formed from bicyclo[3.2.1]oct-2-en-3-ol and from bicyclo[3.2.1]octa-2,6-dienes. In kinetically controlled reactions, which are postulated to proceed via cyclopropylmethyl cations a tendency can be seen towards formation of products retaining the cyclopropane ring. This case is achieved through loss of one of the protons at C4 of A. 

When trifluoroacetic acid was added to butylcyclopropane derivatives 12, Markovnikov products were obtained predominantly. Treatment of cyclopropane with concentrated sulfuric acid yielded propanol. With the deuterated acid, D2SO4, deuterium was found at all three carbon atoms presumably due to the formation of a protonated cyclopropane intermediate. When exo-tricyclo[3.2.1.0 ]octane (13) was treated with deuterated sulfuric acid an end-on attack of the deuterium ion at the most strained bond with inversion of configuration to give 14 was observed. 

Treatment of ent/o-tricyclo[3.2.1.0 ]octane with mercury(II) acetate as electrophile gave endo-4-(acetoxymercurio)-e tfo-2-methoxybicyclo[3.2.1]octane (18a) as the sole product, which was reduced with sodium amalgam in sodium deuteroxide to the corresponding 4-deuterio derivative 18b.83,84 Using the e co-isomer as the substrate gave a 1 1 mixture of exo-[4- HJ-exo-2-methoxybicyclo[3.2.1]octane (19b) and 5yn-7- [ H,]-methyl -ex o-2-methoxybicyclo[2.2.1]hep-tane (20b) after reduction. ... 

Another extensively studied polycycle is the tricyclo[3.3.0.0 ]octan-3-one system 19 which can be converted to 8-methylbicyclo[3.3.0]octan-3-one derivatives 20 upon treatment with lithium dimethylcuprate. Lithium diphenylcuprate reacted in the same way." " ... 

Diazo-compounds can in turn be generated photochemically from sodium salts of toluenesulphonyl hydrazones. Irradiation of the cyclobutane tosylhydrazone (44) gave trans-tricyclo[5.1.0.0 ]-octane (45 R=Me) by the pathway shown in Scheme 4 44 the tricycle (45 R=H) can also be obtained by photoelimination of nitrogen from the diazatricyclo[ 5.2.1.0 4]decene (46). The unexpected conversion of the anthracenocycloheptatriene derivative (47) into triptycene with loss of one carbon atom was observed on irradiation in tetrahydrofuran 4 the mechanism of this unusual reaction remains obscure and merits further investigation, but neither 1-triptycenyl nor 2-triptycenyl carbene appears to be an intermediate in this transformation. 

In another example, irradiation of 2-benzoylbicyclo[2.2.2]octane (286) in cyclohexane results primarily in the formation of the Norrish type II (Section 6.3.4) photoelimination product 287 (Scheme 6.124).965 In contrast, 2-benzoyl-2-methylbicyclo[2.2.2] octane (288) undergoes complete and stereoselective conversion to the tricyclo [3.3.1.02,7]nonane 289.965 The eclipsing interactions between the methyl and phenyl groups in the cxo-2-methyl-substituted derivative slow the hydrogen abstraction step by two orders of magnitude and presumably the same interactions enhance the probability of cyclization. 

Numerous new examples of cyclopentenone synthesis from acetylenehexacarbonyl-dicobalt complexes and norbornene derivatives have been disclosed there is evidence of steric control, and the bulky trimethylsilyl group can be employed as a removable direction-determining group to allow synthesis of 3- instead of 2-sub-stituted cyclopentenones. Reaction of (731) with sodamide in toluene gave the new octahydro-2,5-methanoazulene system (732 R = CONHj) successive hydrolysis, reduction, and esterification converted (732 R = CONHj) into (732 R = CHjOTs) which, on solvolysis, gave the homoprotoadamantane derivative (733 X = H, R R = CH2) in high yield.The carboxylic acid (732 R = COjH) underwent spontaneous Friedel-Crafts intramolecular acylation on conversion into its acid chloride to give (733 XX = O R R = CHj) and (733 XX = O, R = Cl, R = Me). Reaction of methyl a-bromocrotonate (mixture of E- and Z-isomers) with the enolates of cyclohex-2-enone affords a mixture of stereoisomeric tricyclo-[3,2,l,0 ]octan-6-ones (734 R —R are variously H or alkyl) in moderate yield. The reaction involves double Michael addition and subsequent substitution. 

A high-yield synthesis of the norsemibullvalene derivative (724) has been reported reaction of (724) with methanolic potassium cyanide produces anti-7-cya.no-endo-5-bromonorbornan-2-one in high yield which indicates synthetic scope for stereoselective introduction of nucleophiles at C-7 of the norboman-2-one system. A one-pot synthesis of tricyclo[3,2,l,0 ]octan-6-ones of the type (725), by a bicyclo-annulation procedure from cyclohex-2-enones, has been achieved. " ... 

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