Cyclohex 2 enone

B. Cyclohex-2-enones Cleavage of Exocyclic y,d-Bonds and p -Bonding to <3, -Double Bonds... 

Cyclohex-2-enone- bicyclo [3.1.0] hexan-2-one rearrangement, 318 3a,5o -Cyclo-6/3,19-oxidocholestane, 268 18,20-Cyclo-5a-pregnane-3, 20-diol 3-acetate, 264... 

Photochemical cyclohex-2-enone bicyclo (3.1.0)hexan-2-one rearrangement, 320 Photochemical a-cyclopropyl ketone isomerization, 313... 

A portion of the product was heated to reflux with methanolic sodium methoxide to convert it into the thermodynamic mixture of trans- (ca. 65%) and cis- (ca. 35%) isomers. Small amounts of the isomers were collected by preparative gas chromatography using an 8 mm. by 1.7 m. column containing 15% Carbowax 20M on Chromosorb W, and each isomer exhibited the expected spectral and analytical properties. The same thermodynamic mixture of isomers was prepared independently by lithium-ammonia reduction5 of 2-allyl-3-methyl-cyclohex-2-enone [2-Cyclohexen-l-one, 3-methyl-2-(2-propcnyl)-],6 followed by equilibration with methanolic sodium methoxide. 

High-boiling products found in this procedure and in similar experiments involving cyclohex-2-enone derivatives5 probably result from bimolecular reduction processes.15 3-Methylcyclohexanone, which arises by protonation rather than alkylation of the enolate (and which made up ca. 12% of the volatile products), is probably the result of reaction of allyl bromide with liquid ammonia to form the acidic species allyl ammonium bromide.5 10... 

THF (10 ml) was added to the above solution of TMSLi in HMPA, and the mixture immediately cooled to —78°C. A solution of cyclohex-2-enone 1.5mmol) in THF (1ml) was then added dropwise. After stirring for an additional 5 min, methyl iodide (0.5 ml, excess) was added, and the mixture allowed to warm slowly to 0°C. It was then poured into pentane (50 ml) and washed thoroughly with water (2 x 25 ml). After drying and concentration, the residual oil was distilled to give trans-3-trimethylsilyl-2-methylcyclo-hexanone (97%), b.p. 80°C/1 mmHg (Kugelrohr). 

Conjugate addition, 34-5, 51-2,53, 132, 133 Conjugate hydroxymethylation, 59-60 Copper(n) bromide, 54 Copper([) chloride, 120 Copper(n) chloride, 120 Copper(i) cyanide, 7,52, 53 Copper(i) iodide, 54 Corey s internal quench, 104 Cyanohydrin trimethylsilyl ether, 137 Cycloaddition. 34,112 Cydobutane-l,2-dione, 135 Cyclohept-2-dione, 135 Cyclohex-2-enone, 52,123 Cyclohcxa-1,3-diene, 26 Cyclohexane carboxaldehyde, 22-3,69 73,78... 

A Grignard reaction between cyclohex-2-enone and diisopropyl magnesium chloride was carried out in a micro reactor yielding a keto and enol product each [168],... 

The asymmetric 1,4-conjugate addition of phenyl boronic acids to cyclohex-2-enone was catalysed by the Pd complex 141 (Fig. 2.25). Good to excellent yields and high ee (90-97%) were obtained under mild conditions and low catalyst loadings (rt, 3 mol%)... 

Fig. 2.25 Palladium catalysts and postulated intermediates in the asymmetric conjugate addition of phenyl boronic acids to cyclohex-2-enone...

Hydroxy 3 (nonadec 10 en 2 onyl) benzene = campnospermonol 11 5 Hydroxy 5 (nonadec 10 en 2 onyl)cyclohex 2 enone 12 C25H40O2... 

Isoxazolines 79, obtained from aromatic nitrile oxide cycloadditions to cyclohex-2-enone, reacted with nickel peroxide to give 3-aryl-6,7-dihydro[l] benzoisoxazol-4(5// )-ones 80. In contrast, the corresponding 2-bromocyclohex-2-enone underwent nitrile oxide cycloaddition, followed by dehydrobromination, to afford the regioisomeric 3-aryl-4,5-dihydro[l]benzoisoxazol-7(6//)-ones 81 (Scheme 1.23) (242). 

A titanium(iv) chloride mediated Baylis-Hillman-type or aldol reaction between a-ketoesters and cyclohex-2-enones has been studied (Equation (13)).77 The steric effect of the R2 substituent is crucial for the reaction pathway since the aldol reaction only proceeds with the unsubstituted cyclohexenone (aldol adduct 71 with R2 = H to a small extent the Baylis-Hillman reaction occurs), whereas with the substituted substrate (R2 = Me) gives exclusively the Baylis-Hillman adduct 72. 

Asymmetric induction of the Michael addition of thiols to electron-deficient alkenes (4.6.1) has been achieved in high overall conversion using both free [e.g. 12-20] and polymer-supported [e.g. 21, 22] cinchona alkaloids and their salts [23-25], but with varying degrees of optical purity. The corresponding asymmetric Michael addition of selenophenols to cyclohex-2-enones is promoted by cinchoni-dine to give a chiral product (43% ee) [26],... 

Basic solid liquid two-phase conditions with f-butyl peroxide and N-benzylquininium chloride convert cyclohex-2-enone preferentially into the 2(S),3(S)-oxirane (20% ee) which, upon purification and treatment with hydrazine, yields (S)-cyclohex-2-enol [7]. This reaction contrasts with the direct reduction of cyclohex-2-enone to the /J-isomer by lithium aluminium hydride in the presence of quinine [20]. 

Optically pure 7-oxanorbom-5-en-2-yl derivatives ("naked sugars") are readily available. Substitution of their centers C(3), C(5) and C(6) can be done with high stereo- and regioselectivity in a predictable fashion. The polysubstituted 7-oxanor-boman-2-ones so-obtained can be transformed into D- or L-carbohydrate derivatives, C-nucleoside precursors or polysubstituted cyclohex-2-enones and cyclohexenols (Scheme 12). Stereoselective rearrangements of the 7-oxanorbom-2-yl systems into polyhydroxylated cyclopentyl derivatives are also possible. 

Enehydroxylamine 0-derivatives 149 and 151, prepared from the reactions of A-alkyl-3-(hydroxyamino)cyclohex-2-enone (148, R = H) and iV-alkyl-3-(hydroxyamino)-5,5-dimethylcyclohex-2-enone (148, R = Me) with MsCl (equation 41) and Mc2NC(S)Cl (equation 42), respectively, in the presence of base rearrange spontaneously providing the corresponding [3,3]-sigmatropic rearranged products 150 and 152 in moderate to excellent yield . However, the diethyl phosphate 153 (equation 43) and the O-benzoyl hydroxylamine 154 rearrange under reflux in toluene (equation 44). 

Sensitized photo-oxidation of substituted cyclohexanone silyl enol ethers yields substituted cyclohex-2-enones." For example, menthone may yield (8 X=H) or (15) depending upon the direction of enolization " the corresponding hydroxy-... 

Tanaka K, Mochizuki E, Yasui N, Kai Y, Miyahara I, Hirotsu K, Toda F (2000) Single-crystal-to-single-crystal enantioselective [2-1-2] photodimerization of coumarin, thiocoumarin and cyclohex-2-enone in the inclusion complexes with chiral host compounds. Tetrahedron 56 6853-6865... 

Table 2.1.5.5 Cu-catalyzed enantioselective 1,4-addition of diethylzinc to cyclohex-2-enone 21.

Irradiation of 2-(prop-2-enyloxy)- and 2-(but-2-enyloxy)cyclohex-2-enones gives 2-oxabicy-clo[2.1.1]hexane and -[3.1.1]heptane derivatives, respectively,17 while 2-(but-3-enoyIoxy)- (7, n = 1) and 2-(pent-4-enoyloxy)cyclohex-2-enone (7, n = 2) afford the cyclohexanone-annulated 2-oxabicyclo[3.2.0]heptan-3-one (8, n = 1) and -[4.2.0]octan-3-one (8, n = 2) derivatives, respectively.18... 

Both the reduction potential of 6-substitutcd cyclohex-2-enones and the ionization potential of the alkene control the product ratio of photocycloadducts vs. photoadducts on the one hand,90 and cyclobutane vs. oxetane formation, on the other91 (a similar dependence of the site of reaction as a function of the ionization potential of the alkene has been observed for 1,4-naphthoquinone92). 3- and 2-Alkynylcyclohex-2-enones on irradiation in the presence of alkenes afford both cyclobutane and cyclopentane derivatives.93-94 The regiochemistry of the photoadducts of simple cyclohex-2-enones to cycloalkenes seems to be dependent on the ring size of this latter species.95... 

Among bicyclic cyclohex-2-enones, the formation of tricyclo[4.4.2.01,6]dodecane-2,7-dione from bicyclo[4.4.0]dec-l(6)-ene-2,7-dione and ethene proceeds in 95% yield,101 and that of 8-mcthyl-tricyclo[6.4.0.01,4]dodecan-5-ones from 6-methylbicyclo[4.4.0]dec-l(2)-en-3-one and ethene in 77% yield,102 respectively. Steroids containing cyclohex-2-enone subunits,103 e.g. 17/ -acetoxy-5a-androst-1 -en-3-one,104 often afford /raw-fused cycloadducts with alkenes. When such reactions are performed on silica gel, complete reversal of stereochemistry to that observed in solution can occur.105... 

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