Bicyclo octanones

An argon-degassed solution of 1.24g (0.01 mol) 75 and 8.4g (0.1 mol) 2,3-dimethylbut-2-ene in benzene (100 mL) is irradiated with a 250-W Hg-lamp in a double-walled immersion well using a filter solution (7g Pb(NO3)2-l-750g NaBr/lOOmL water, cut-off at X = 340 nm) as coolant for 12 h. After evaporation of the solvent and excess alkene the residue (2.0 g) consisting of a 3 1 mixture of trans- and m-fused bicyclo-octanones 76 and 77 is refluxed for 2h in a solution of 4g KOH in methanol (100 mL). After cooling to r.t. the mixture is neutralized with 5% aq. HC1, the methanol evaporated and the residue extracted three times with ether (25 mL). The... 

The conformational effects operative in the photochemistry of bicyclo-octanones (47) have been studied.48 The authors argue that several products should be possible if conformational effects control the fate of the biradicals formed by the Norrish Type I fission. However, if hydrogen abstraction is faster than conformational relaxation, the products must be derived from that conformation, e.g. (48), present immediately after bond fission. The results obtained... 

Diacetates of 1,4-butenediol derivatives are useful for double allylation to give cyclic compounds. l,4-Diacetoxy-2-butene (126) reacts with the cyclohexanone enamine 125 to give bicyclo[4.3.1]decenone (127) and vinylbicy-clo[3.2.1]octanone (128)[85,86]. The reaction of the 3-ketoglutarate 130 with cij-cyclopentene-3,5-diacetate (129) affords the furan derivative 131 [87]. The C- and 0-allylations of ambident lithium [(phenylsulfonyl)methylene]nitronate (132) with 129 give isoxazoline-2-oxide 133, which is converted into c -3-hydroxy-4-cyanocyclopentene (134)[S8]. Similarly, chiral m-3-amino-4-hyd-roxycyclopentene was prepared by the cyclization of yV-tosylcarbamate[89]. 

Base-induced rearrangement of bicyclo[2.2.2]octane oxide 67 gives predominantly bicyclo[2.2.2]octanone 68 (Scheme 5.15), which once again indicates that close proximity between the carbenoid center and the C-H bond into which it may insert is important if such an insertion is to occur [30]. In comparison, the sense of product distribution is reversed for the related substrate bicyclo[2.2.2]octadiene oxide 70 on treatment with LDA [15, 22], alcohol 72 being the favored product. 

The retrosynthetic analysis led to the bridged bicyclo[2.2.2]octanone 2 as the key intermediate which was synthesised from an epimeric mixture of ethyl bicyclo[2.2.2]oct-5-ene-2-carboxylate (4) as shown in Scheme 13.1.4. 

Dienylacetates give bicyclo[3.3.0]octanones in reasonable yields and diastereoselectivity, depending on conditions, temperature, and pressure, though the main product of these reactions often results, from premature termination of cascade (Equation (38))/ ... 

Ranu, B.C., Guchhait, S.K., Gosh, K. and Patre, A., Construction of bicyclo[2.2.2]octanone systems by microwave-assisted solid phase Michael addition followed by AI2O3-mediated intramolecular aldolisation. 

We note die earlier paper by Becker and Roth65 that presented a value for bicyclo[2.2.2]octanone (herein named ewdo-ethylenecyclohexanone) that differed from die just-cited more recent one116 by ca 4 kJmol-1. 

These bicyclo[4.2.0]octanones also undergo aza-ring expansion to lactams. Beckmann rearrangement of the oxime of a typical bicyclic butanone (1) results in an octahydroisoindolone (2), whereas rearrangement of the methylnitrone (3) with tosyl chloride (4, 510 511 6, 598) proceeds in the opposite direction to give an octahydroindolone (4) as the only product.2... 

Bicyclic cyclotrigermanes, thermolysis, 3, 793 Bicyclic imidazoles, via intramolecular C-H functionalizations, 10, 138 Bicyclic siloxanes, rational synthesis, 3, 655 Bicycloctasilane dianion, preparation, 3, 466468 Bicyclo[5.3.0]decadiene, via [5+2]-cycloadditions, 10, 613 Bicyclo[5,3,0]-decanes, via Pauson-Khand reaction, 11, 361 Bicyclononasilane anions, preparation, 3, 466-468 Bicyclo[3.3.0]-octanones, via carbonylative carbocyclization, 11, 427... 

Interestingly, zirconacyclopentane 246 formed by the reaction of 1,6-heptadiene with the Zr complex has the firms ring junction mainly [108]. It should be noted that the preparation of the trans ring junction in the bicyclo[3.3.0]octane system by other means is difficult. Carbonylation of 246 affords trans-fuzed bicyclo[3.3.0]octanone 247 [109,111]. The diacetoxy compound 248 is obtained by oxidative cleavage of 246. Protonation affords the frans-dimethylcyclopentane skeleton. Similar reactions occur with 1,6-enynes, and Pauson Khand-type cyclopentenone synthesis is possible by carbonylation. 

In the optical resolution of bicyclo[2.2.1]heptanones (87a, 88-90), bicyclo[2.2.2]- octanones (91-94) and bicyclo[3.2.1]octanone (95) by complexation with various chiral host compounds, some best host-guest combinations were found. Resolutions of 88, 89, 90, and 92 were accomplished efficiently by complexation with 3 to give (+)-88 (100% ee, 33%), (-)-89 (100% ee, 16%), (+)-90 (100% ee, 60%), and (-)-92 (100% ee, 41%), respectively, in the optical and chemical yields indicated.36 However, resolutions of 93 and 95 were accomplished efficiently by complexation with 8a to give optically pure (-)-93 and (-)-95 in 56 and 48% yields, respectively. On the other hand, resolution of 94 can be accomplished only by complexation with 15c to give finally (-)-94 of 100% ee in 31% yield.36 Mechanism of these chiral recognition in the inclusion complex crystal has been studied by X-ray analysis.36 Nevertheless, none of 3,8a and 15c is applicable to the resolution... 

Toda, F., Tanaka, K., Marks, D., and Goldberg, I. (1991) Optical Resolution of Bicyclo[2.2.1]heptanone, Bicyclo[2.2.2]octanone, and Bicyclo[3.2.1]octanone Derivatives by Inclusion Complexation with Optically Active Host Compounds, J. Org. Chem., 56, 7332-7335. 

Die Belicbtung von 2-Cydohexenon in iiberschussigem Isobutylen bei —40 bis —70°C fiihrt zu den Bicyclo[4,2,0]octanon-(2)-Derivaten 71, 72 und 73 neben geringen Mengen an ungesattigten Ketonen (Formeln 74 und 75) (78). 

Sml2 can be also used for the same ring-expansion reaction. Thus, radical ring-expansion reaction of bicyclo[4.2.0]octanone (274) promoted by Sml2 provides a mixture of cyclooctanol (275a) and lactone (275b) (eq. 3.111). In this case, C02Me, CN, and Ph... 

Benzoyl-4-methylbicyclo[2.2.2]oct-5-en-2-one 71, prepared by the Diels-Alder reaction of 2-trimethylsioxy-4-methyl-l, 3-cydohexadiene with benzoylethyne, underwent ODPM rearrangement in the absence of a sensitizer to give 72 in good yield (Scheme 4.29). The irradiation of 72 in 40% triethylamine (TEA)-methanol gave a bicyclo[3.2.1]octanone 73 in 86% yield. On direct irradiation, a one-pot conversion... 

The alkylation of acyclic imines with electrophilic alkenes such as acrylonitrile, methyl acrylate or phenyl vinyl sulphone is also sensitive to steric effects and again, as a consequence, only mono-alkylation occurs398. The regioselectivity of the reaction in methanol varied from 100% attack at the more substituted a-position to 70% attack at the less substituted a -position depending upon the steric inhibition manifested and the stabilization of the competing secondary enamine tautomers (vide infra) (Scheme 204). In contrast, the reaction of butanone and other methyl ketone imines with phenyl vinyl ketone occurs twice at the more substituted a-position but this is then followed by a double cyclization process (Scheme 205). Four carbon-carbon bonds are formed sequentially in this one-pot synthesis of the bicyclo[2.2.2]octanone 205 from acyclic precursors399,400. 

Bicyclo[3.3.0]octanones are photolabile in their own right and experience ring opening when irradiated. Coyle has demonstrated that the overriding factor in product formation from the diradical intermediates is the distance between the hydrogen atom which is transferred and the radical center to which it migrates.l96)... 

Microwave irradiation of a mixture of cyclohexenones and ethyl acetoacetate adsorbed on the surface of solid lithium 5-(2)-prolinate leads to the stereoselective construction of bicyclo[2.2.2]octanone (69) systems through Michael addition and subsequent intramolecular aldolization (Ranu et al., 2000). Electron-rich aromatic compounds react with formaldehyde and a secondary amine under solvent-free condition and microwave irradiation in a microwave oven to produce amino ethylated products (70) in good to excellent yields (Mojtahedi et al., 2000). 

Oxiranecarboxylic acid Bicyclo[2.2.2]octanone Propynoic acid... 

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