Ketone functionality

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

Like aldehydes ketone functions take precedence over alcohol functions double bonds halogens and alkyl groups m determining the parent name and direction of numbering Aldehydes outrank ketones however and a compound that contains both an aldehyde and a ketone carbonyl group is named as an aldehyde In such cases the carbonyl oxy gen of the ketone is considered an 0x0 substituent on the mam chain... 

Ketones may also be named using functional class lUPAC nomenclature by citing the two groups attached to the carbonyl m alphabetical order followed by the word ketone Thus 3 methyl 2 butanone (substitutive) becomes isopropyl methyl ketone (functional class)... 

The systematic lUPAC name of ethyl acetoacetate is ethyl 3 oxobutanoate The presence of a ketone carbonyl group is indicated by the designation oxo along with the appro priate locant Thus there are four carbon atoms m the acyl group of ethyl 3 oxobutanoate C 3 being the carbonyl carbon of the ketone function... 

In the early work on the synthesis of prostaglandins, zinc borohydride was used for the reduction of the 15-ketone function and a 1 1 mixture of epimeric 15(S)- and 15(/ )-alcohols was generally obtained. Subsequent studies led to reaction conditions for highly selective reduction to the desired 15(S)-alcohol. Some of the results are summarized in the following table. The most practical method is E which utilizes borane as the stoichiometric reductant and a chiral, enzyme-like catalyst which is shown. 

If the ketone function is adjacent to a hydrogen-bearing asymmetric center, the compound can undergo epimerization. In steroids with a normal skeletal configuration (8/3, 9a, 14a) there is no detectable epimerization at C-8 or C-9 during the exchange of and 11- ketones. 

Enolizalion of conjugated or /3,y-unsatiirated enones and dienones in O-deiiterated solvents facilitates the introduction of deuterium labels into positions as far as three and five carbon atoms away from a given ketone function. Exchange of the activated hydrogens in androst-4-en-3-one (12) provides a good illustration of the potential of this method. Saturation of the double bond (section V) in the deuterated enone (13) followed by back exchange of the a-deuteriums (section II-B) proves to be an excellent method for the preparation of 6,6-d2-5a-androstan-3-one (15). ... 

The A -6-ketone functionality in polyhydroxy cholestanes is common to all the insect moulting hormones of the ecdysone type. Therefore, there has recently been considerable interest in the introduction of A -double bonds into 6-ketones. The different approaches that follow illustrate the utility of isomerization, rearrangement, and blocking groups. 

Magnesium triflate and zinc triflate are outstanding catalysts for the intro duction of the thioketal group for the protection of the ketone function [126] The reaction of a variety of ketones with ethane 1,2-dithiol in the presence of these triflates proceeds under mild conditions to form the corresponding thioketals in high yield (equation 62)... 

When formation of either the five- or six-membered ring was possible for N-chloroamine 37, only the five-membered ring was conducive under the Hofmann-Ldffler-Freytag reaction conditions, forming exclusively 6-ethyl-6-aza-bicyclo[3.2.1]-octane (38). No 2-ethyl-2-aza-bicyclo[2.2.2]-octane (39) was observed. On the other hand, 2-methyl-2-aza-bicyclo[2,2.2]octan-6-one (41) was installed by UV irradiation of a solution of A -chloroamine 40 in TFA. Ironically, when the ketone functionality on 40 was protected as its ethylene ketal group, the resultant steric interactions completely prohibited the classic Hofmann-Loffler-Freytag reaction. 

Ketose (Section 25.1) A carbohydrate with a ketone functional group. 

In the third sequence, the diastereomer with a /i-epoxide at the C2-C3 site was targeted (compound 1, Scheme 6). As we have seen, intermediate 11 is not a viable starting substrate to achieve this objective because it rests comfortably in a conformation that enforces a peripheral attack by an oxidant to give the undesired C2-C3 epoxide (Scheme 4). If, on the other hand, the exocyclic methylene at C-5 was to be introduced before the oxidation reaction, then given the known preference for an s-trans diene conformation, conformer 18a (Scheme 6) would be more populated at equilibrium. The A2 3 olefin diastereoface that is interior and hindered in the context of 18b is exterior and accessible in 18a. Subjection of intermediate 11 to the established three-step olefination sequence gives intermediate 18 in 54% overall yield. On the basis of the rationale put forth above, 18 should exist mainly in conformation 18a. Selective epoxidation of the C2-C3 enone double bond with potassium tm-butylperoxide furnishes a 4 1 mixture of diastereomeric epoxides favoring the desired isomer 19 19 arises from a peripheral attack on the enone double bond by er/-butylper-oxide, and it is easily purified by crystallization. A second peripheral attack on the ketone function of 19 by dimethylsulfonium methylide gives intermediate 20 exclusively, in a yield of 69%. 

Benzo-annulated dihydrooxepinones are readily accessible (see Houben-Weyl, Vol. 6/4, pp453) and can be converted to the corresponding hydroxy derivatives by reduction of the ketone function. The elimination of water from 10,ll-dihydrodibenz[fc,/]oxepin-10-ol to give 1 was accomplished with /t-toluenesulfonic acid.165-167... 

Instead of reducing the ketone function, a lithium organic reagent, e.g. phenyllithium, can be added followed by an acid-catalyzed elimination of water to give product 3.85 This procedure allows the introduction of various substituents. By this method 3-[2-(dimethylamino)ethoxy]-... 

The different reactivity of the ketone functions has also been demonstrated by the reaction of 2,7-dimethyl-4-phenyl-l-benzoxepin-3,5(2f/,4//)-dione with diazomethane which gives a mixture of the two monomelhylated products 10 and 11. In both compounds, the second methyl group is introduced by deprotonation with potassium tm-butoxide followed by the addition of methyl fluorosulfonate.177... 

Derivatives of dibenz[6,/]oxepin-10,l 1-diol can also be obtained from the respective dionc after reduction of one ketone function to the alcohol. The acetylation of dibenz[Z>,/]oxepin-10,11-dione in the presence of zinc affords 10,1 l-diacetoxydibenz[/r,/]oxepin (14).179... 

When the hexamethylene bridge already contains a ketone function, the corresponding cyclo-decenedione derivative 3 is obtained upon regioselective oxidation of the C-C double bond a with potassium permanganate and sodium periodate.38... 

Ley and Middleton synthesized ketone-functionalized lactam complexes 260 (Scheme 2.64) by sonication of vinylaziridines 259 with Fe2(CO)9 in benzene. These complexes were easily converted into the corresponding (3-lactams 261 by stereoselective addition of nucleophiles such as NaBH4 or trialkylaluminium to the carbonyl group followed by decomplexation with Me3NO [96]. 

The aldehyde or ketone functionalities in the Michael adducts are restored by ozonolysis of the hydrazone moiety resulting in am/-3,4-disubstituted-5-oxoalkanoates 1. 

The epoxyketone 3 is a versatile precursor for a variety of tricycloundecane systems having a p,y-unsaturated carbonyl chromophore, which are not so readily accessible. The contiguous epoxy ketone functionality and the double bond present in the five-membered ring provide opportunities for further manipulation. Adduct 3 may be transformed into a variety of molecular frameworks such as linearly fused cis anti cis tricyclopentanoids, protoilludanes, and marasmanes in a stereoselective fashion after suitable chemical and photochemical manipulation.13... 

Esters, acid chlorides, nitriles 56) react with carbanionic sites — provided their nucleophilicity is high enough — to yield terminal ketone functions. If excess reagent is used, further attack of the ketone by carbanionic sites can be prevented. 

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