Ketones selectivity

Table 3 shows the toxicological properties of selected ketones. A detailed review of the physiological effects of exposure to methyl ethyl ketone and methyl isobutyl ketone has been documented (6). 

Even more highly selective ketone reductions are earned out with baker s yeast [61, 62] (equations 50 and 51) Chiral dihydronicotinamides give carbonyl reductions of high enantioselectivity [63] (equation 52), and a crown ether containing a chiral 1,4-dihydropyridine moiety is also effective [64] (equation 52). 

Selective ketone protection The -CHO group is converted in Step 1 to a siloxysulfonium salt [R CH(OTMS)S Me2 OTf] that is reconverted to an aldehyde group in Step 3." ... 

Sample Time (h) Si/M ratio Cyclohexane Conversion (%) TBHP Conversion (%) Mono- oxygenated selectivity (%) Ketone/ Alcohol ratio... 

Winer, A.M., Lloyd, A.C., Damall, KR., Pitts, Jr., J.N. (1976) Relative rate constants for the reaction of the hydroxyl radical with selected ketones, chloroethenes, and monoterpene hydrocarbons. J. Phys. Chem. 80, 1635-1639. 

Other related chiral erythro selective ketone enolates (iS -139 and (i )-139, readily prepared from (5)- and (i )-atrolactic acid, also exhibit good aldol diastereoface selection (3). From the data summarized in Table 34a, the influence of asymmetry in both condensation partners (entries C-F) has been amply demonstrated. The... 

Jones, P. et al. (2008) A novel series of potent and selective ketone histone deacetylase inhibitors with antitumor activity in vivo. Journal of Medicinal Chemistry, 51, 2350-2353. 

The [Con(bipy)2 ]2+ species has also been reported to activate hydrogen peroxide and ter -butyl hydroperoxide for the selective ketonization of methylenic carbons, the oxidation of alcohols and aldehydes, and the dioxygenation of aryl olefins and acetylenes (36). Later reports (37), however, while confirming that the cobalt complexes did indeed cata-... 

Table 6. Reaction of ethyl cyanoacetate with selected ketones using aminopropyl/phenyl containing HMS.

Thus far we have discussed numerous examples whereby selective ketone formation has been achieved through organometallic acylation. The problem was approached by choosing a less nucleophilic organometallic which can be acylated but does not interact wiA the desired product. Thus far, few reagents with this type of selectivity have been found (organocuprates). Most often, the strategy was to either preserve the tetrahedral intermediate formed upon nucleophilic addition or to activate the substrate... 

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