Ketone carbocyclic

In 1998, Yang and coworkers reported a series of (7 )-carvone derived ketones (63) containing a quaternary center at and various substituents at (Fig. 22) [119]. The ees of fran -stilbene oxide varied with different para and meta substituents when 63b was used as the catalyst. The major contribution for the observed ee difference is from the n-n electronic repulsion between the Cl atom of the catalyst and the phenyl group of the substrate. The substitution at also influences the epoxidation transition state via an electrostatic interaction between the polarized C -X bond and the phenyl ring on franx-stilbene (Table 6, entries 3-7, 10-14). In 2000, Solladie-Cavallo and coworkers reported a series of fluorinated carbocyclic ketones... 

Imines of acyclic and C10- to C15-membered carbocyclic ketones are prepared under the conditions described for cyclohexanone imines using trifluoromethanesulfonic acid or trifluoroacetic acid as additional catalyst. The reaction often takes several days in refluxing benzene or toluene9. 

Many 1,2,3-selenadiazoles have been prepared as intermediates for the ultimate preparation of other organic compounds or for biological activity evaluation [6], The most general, extensively applied method is based on the oxidation of semicar-bazones, mostly derived from aromatic and carbocyclic ketones, by selenium dioxide [6, 14, 188-191], Synthesis of 4-(2-naphthyl)-l,2,3-selenazole (117) from semicarbazone (116) is an example (Scheme 36). 

There are an immense number of examples of aldol condensations of aromatic carbocyclic ketones with aromatic aldehydes. These systems usually give excellent yields of aldol condensation products, because the starting ketone can usually enolize in only one direction and because the ketones do not afford... 

Several examples of intramolecular dicarbonylative addition of 1-alkenyl halides to double bonds are reported to give cyclopen tenones, cyclohexenones, or other carbocyclic ketones with additional carboxylic ester functions in the side chains. These reactions can either be catalyzed by palladium(II) catalysts26-28 or by tctracarbonylnickel29. 

Oximes of carbocyclic ketones in hydrogen carbonate solution are oxidized by jV-bromosuccinimide to 1-bromo-l-nitrosocycloalkenes, which are converted by nitric acid into 1-bromo-l-nitrocycloalkanes in 40-70% yield, and the latter products can be reduced by potassium iodide in methanol or by sodium tetra-hydridoborate to the corresponding nitrocycloalkanes.197 Oximes of aromatic aldehydes may be converted by dinitrogen tetraoxide into the dinitro compounds.198 tt-Nitrobenzaldehyde oxime is converted by dinitrogen tetraoxide into oc,ot, -trinitrotoluene (phenyltrinitromethane) in 77% yield.199... 

The carba-disaccharide 81 has been designed as an antigen for preparing glycoside-bond forming catalytic antibodies with catalytic groups. In its synthesis the addition of an acetylide anion to a carbocyclic ketone, followed by an OH Ns replacement, formed the key steps. 

Li et al. developed a new route to quinolinone synthesis catalyzed by Cu(acac)2 through oxidative (sp3)-H functionalization-carbocyclization-ketonization cascade (Scheme 8.94). This efficient protocol provides a new pathway to synthesize the quinolinone framework via implanting an oxygen atom from molecular oxygen. The desired quinolinones could be obtained in moderate to good yields under the mild conditions [166]. 

At higher temperatures the mixture of 10 and methyl vinyl ketone yields the 1,4-carbocyclic compound as described previously. Methyl isopropenyl ketone (5), ethyl acetylacrylate (d), 2-cyclohexenone (21), and 1-acetyl-1-cyclohexene (22) also undergo this type of cyclization reaction with enamines at higher temperatures. This cycloalkylation reaction occurs with enamines made of strongly basic amines such as pyrrolidine, but the less reactive morpholine enamine combines with methyl vinyl ketone to give only a simple alkylated product (7). Chlorovinyl ketones yield pyrans when allowed to react with the enamines of either alicyclic ketones or aldehydes (23). 

The reaction of cyanogen azide with enamines of cyclic ketones to yield a cyanoamidine with one less member in the carbocyclic ring represents a potentially valuable method of ring contraction under mild conditions (199a). The reaction probably proceeds first by 1,3 cycloaddition of the azide to the enamine followed by rearrangement and elimination of a molecule of nitrogen. 

The asymmetric Michael addition of chiral nonracemic ketone enolates has most frequently been used as part of the Robinson annulation methodology in the synthesis of natural products171-172. The enolates are then derived from carbocyclic chiral ketones such as (+)-nopinone, (-)-dihydrocarvone, or (-)-3-methylsabinaketone. 

An interesting strategy for the diastereoselective synthesis of five-membered carbocycles was achieved by the reaction of alkenylcarbene complexes and lithium enolates derived from simple methyl ketones [79]. The use of more or less coordinating solvents (THF or Et20) or the presence of cosolvents such as PMDTA allows the selective synthesis of one or the other diastereoisomer of the final cyclopentene derivative (Scheme 32). 

Seven-membered carbocycles are also available from the reaction of alkenylcarbene complexes of chromium and lithium enolates derived from methyl vinyl ketones [79b] (Scheme 65). In this case, the reaction is initiated by the 1,2-addition of the enolate to the carbene complex. Cyclisation induced by a [1,2]-migration of the pentacarbonylchromium group and subsequent elimination of the metal fragment followed by hydrolysis leads to the final cyclo-heptenone derivatives (Scheme 65). 

Several steps are involved in these reactions. First, the enolate of the (1-kelocstcr opens the cyclopropane ring. The polarity of this process corresponds to that in the formal synthon B because the cyclopropyl carbons are electrophilic. The product of the ringopening step is a stabilized Wittig ylide, which can react with the ketone carbonyl to form the carbocyclic ring. 

The indium-mediated allylation of trifluoroacetaldehyde hydrate (R = H) or trifluoroacetaldehyde ethyl hemiacetal (R = Et) with an allyl bromide in water yielded a-trifluoromethylated alcohols (Eq. 8.56).135 Lanthanide triflate-promoted indium-mediated allylation of aminoaldehyde in aqueous media generated (i-airiinoalcohols stereoselectively.136 Indium-mediated intramolecular carbocyclization in aqueous media generated fused a-methylene-y-butyrolactones (Eq. 8.57).137 Forsythe and co-workers applied the indium-mediated allylation in the synthesis of an advanced intermediate for azaspiracids (Eq. 8.58).138 Other potentially reactive functionalities such as azide, enone, and ketone did not compete with aldehyde for the reaction with the in situ-generated organo-indium intermediate. 

Moreover, the authors were able successfully to apply this process to the synthesis of the antibiotic (+)-CP-263,114 (2-912) (Scheme 2.203) [454]. Transformation of the bromide 2-908 into the vinyl Grignard reagent 2-909, followed by addition to the ketone 2-910, led to the bridged carbocyclic compound 2-911 which was then transformed into the target compound within a few steps. 

Another interesting example of a photochemi-cally induced domino process is the combination of the photocyclization of aryl vinyl sulfides with an intramolecular addition as described by Dittami et al. [901 as intermediate a thiocarbonyl ylide can be assumed. The domino-Norrish I-Knoevenagel-allyl-silane cyclization developed by us allows the efficient stereoselective formation of 1,2-trans-subsituted five- and six-membered carbocycles.1911 A photochemical cycloaddition of enamino-aldehydes and enamino-ketones with the intermediate formation of an iminium salt followed by addition to allylsilanes gives access to novel bicyclic heterocy-des. New examples of photochemically induced... 

---