3721-60-6Relevant articles and documents
Facile synthesis and ring-opening cross metathesis of carbo- and heterocyclic bicyclo[3.2.1]oct-6-en-3-ones using gaseous olefinic reaction partners
Mihovilovic, Marko D.,Groetzl, Birgit,Kandioller, Wolfgang,Snajdrova, Radka,Muskotal, Adel,Bianchi, Dario A.,Stanetty, Peter
, p. 463 - 470 (2006)
The title compounds were prepared by a facile [4+3]-cycloaddition strategy involving sonochemistry. The oxyallyl species required for the reaction with the corresponding diene was generated from a suitable perbromo ketone with activated zinc under sonific
Synthesis of tetrahydrofuran-based natural products and their carba analogs via stereoselective enzyme mediated Baeyer–Villiger oxidation
Rudroff, Florian,Bianchi, Dario A.,Moran-Ramallal, Roberto,Iqbal, Naseem,Dreier, Dominik,Mihovilovic, Marko D.
, p. 7212 - 7221 (2016/10/29)
In this work we present efficient formal syntheses of several biologically interesting natural products (showdomycin, goniofufurone, trans-kumausyne) and their novel carba analogs by applying different Baeyer–Villiger monooxygenases. This strategy provides access to tetrahydrofuran-based natural products, C-nucleosides and both antipodes of the corresponding carba analogs in high optical purities (up to >95% ee) starting from simple achiral and commercially available building blocks (tetrabromoacetone, furan and cyclopentadiene). The striking key features of this chemo-enzymatic approach are the introduction of four stereogenic centers in as few as three reaction steps within a desymmetrization approach and the short-cut of several reaction sequences by the implementation of a biocatalytic step.
Methoxy- and Dichloro-Substituted Oxyallyl Intermediates
Foehlisch, Baldur,Krimmer, Dieter,Gehrlach, Eberhard,Kaeshammer, Dietmar
, p. 1585 - 1594 (2007/10/02)
Solvolysis of 1-chloro-1-methoxy-2-propanone (1a) and 3-methoxy-2-oxopropyl mesylate (2c) in basic 2,2,2-trifluoroethanol affords the same product, 1-methoxy-1-(2,2,2-trifluoroethoxy)-2-propanone (6), by way of an enolization-ionization mechanism.The oxyallyl intermediate 3 can be trapped by furan and 2-methylfuran in a cycloaddition. 1,1,3-Trichloro-2-propanone (13) reacts with basic trifluoroethanol in a Favorskii rearrangement to give the trifluoroethyl ester of cis-3-chloroacrylic acid (19).The intermediate, 1,3-dichloroallylium-2-olate (20), combines with furan, 2,5-dimethylfuran, cyclopentadiene, and spirohexadiene to form the cycloadducts 22a-d in good yields.In contrast, 1,3-dichloro-2-propanone (10) does not follow the enolization-ionization pathway; in LiClO4/Et2O/NEt3 the selfcondensation product 12 arises.
13C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated system: 3,3-dimethylbicyclooct-6-en-2-one
Antoniadis, Greg A.,Clements, Michael T. M.,Peiris, Sriyawathie,Stothers, J. B.
, p. 1557 - 1562 (2007/10/02)
Under homoenolization conditions (t-BuO-/t-BuOH/185 deg C), 3,3-dimethylbicyclooct-6-en-2-one (5) is converted into six products through three rection pathways.The major product, 3,3-dimethylbicyclooctan-2-one, arises by unidirectional β-enolate rearrangement of 5 to the isomeric unsaturated ketones, which (a) undergo efficient reduction to 2, by single electron transfer, and (b) suffer Haller-Bauer cleavage to two isomeric 2,2-dimethyl-3-cyclopentenylpropanoic acids.In competition with these processes is the reversible conjugate addition of t-BuO- to 5 to furnish the 6-tert-butoxy derivative, which undergoes β-enolate rearrangement to two isomeric ketones.The structures of these products were established primarily from their 1H and 13C magnetic resonance spectra.
Cycloaddition Reactions of Allenyl Cations with Cyclopentadiene
Mayr, Herbert,Halberstadt-Kausch, Inge K.
, p. 3479 - 3515 (2007/10/02)
Propargyl halides R1-C=-C-CR2R3X (14) and cyclopentadiene react with zinc halide catalysis in ether/dichloromethane solution to give 3-halogenobicycloocta-2,6-dienes 13 (R1 = alkyl) or 5-(α-halogenobenzylidene)norbornenes 15 (R1 = aryl).The reactions are interpreted by stepwise - and -cycloadditions of intermediate allenyl cations 1, proceeding via propargylcyclopentenyl cations 5 and bicyclic vinyl cations 9 or 12.If the reactions are initiated by equimolar amounts of silver trifluoroacetate, quenching products of all postulated intermediates are isolated.The relative energies of the intermediate carbenium ions are estimated on the basis of force field calculations and of gas phase stabilities of simple carbocations.Stereochemical studies indicate that the addition reactions proceed via the compact transition state 42 rather than 41.The zinc chloride catalysed reaction of propargyl chloride 14e with cyclopentadiene yields the 2:1 product 17 (structurally assigned by X ray analysis) in addition to the 1:1 product 15e.The formation of 17 is rationalised by a -cycloaddition of allenyl cation 1 with cyclopentadiene.
