Ketones, functionalized oxidation

The methoxymethyl ether protecting groups of 33 were then cleaved using triphenylphosphine and carbon tetrabromide. The resulting hydroquinone function was oxidized by palladium on carbon under an atmosphere of air to afford the quinone 52 (70 %). A two-step procedure was implemented to install the diazo function. First, the ketone function of 52 was condensed with N,N -bis( tert-butyldimethylsilyl)hydrazine in the presence of scandium triflate, which formed the Af-tert-butyldimethylsilyl hydrazone 53. The hydrazone (53) was then oxidized using difluoroiodobenzene to afford kinamycin C (3) in 35 % yield. [Pg.50]

The reaction of allenes with peracids and other oxygen transfer reagents such as dimethyldioxirane (DM DO) or hydrogen peroxide proceeds via allene oxide intermediates (Scheme 17.17). The allene oxide moiety is a versatile functionality. It encompasses the structural features of an epoxide, an olefin and an enol ether. These reactive intermediates may then isomerize to cyclopropanones, react with nucleophiles to give functionalized ketones or participate in a second epoxidation reaction to give spirodioxides, which can react further with a nucleophile to give hydroxy ketones. [Pg.985]

A catalytic route using a manganese (III) complex has been developed for a-hydroxylation of ketones avoiding the use of water or a protic solvent mixtures of a-hydroxyketones and their silyl derivatives were formed in excellent yield. By using a chiral pyrrolidine-based manganese (III) complex as catalyst, asymmetric oxidation was effected, with enantiomeric excess varying from 14 to 62% [30], Another kind of a-functionalized ketones resulted from silyl enol ethers which after the addition of IOB.BF3 were treated with triethyl phosphite a-ketophosphonates were obtained in this way [31] ... [Pg.88]

Alkyl halides (particularly bromides) undergo oxidative addition with activated copper powder, prepared from Cu(I) salts with lithium naphthalenide, to give alkylcopper species10. The alkyl halides may be functionalized with ester, nitrile and chloro functions ketone and epoxide functions may also be tolerated in some cases11. The resulting alkylcopper species have been shown to react efficiently with acid chlorides, enones (conjugate addition) and (less efficiently) with primary alkyl iodides and allylic and benzylic bromides (equations 5 and 6). If a suitable ring size can be made, intramolecular reactions with epoxides and ketones are realized. [Pg.1278]

Antoniotti and Dunach have reviewed the stoichiometric and catalytic oxidation of epoxides and their scope in organic synthesis, with particular focus on the Bi/02-catalyzed oxidation developed in their group. Such reactions can lead to either the oxidative cleavage of the epoxy carbon-carbon bond (giving carbonyl compounds or carboxylic acids (Scheme 57, Equation 14) or alternatively the formation of a-functionalized ketones when the C-C bond of the epoxide remains uncleaved (Scheme 57, Equation 15) <2003S2753>. [Pg.281]

Oxidation of n-butane. In the presence of oxygen, Co(l 1) is converted into Co(lll), the actual catalyst for oxidation of alkanes by oxygen thus oxidation of n-butane by Co(lll) ion at 100° at a pressure of 17-24 atm. gives acetic acid (83.5% yield) together with traces of n-butyric acid, propionic acid, and methyl ethyl ketone. Oxidation of n-pentane under similar conditions gives acetic acid (48% yield) and propionic acid (27% yield). Isobutane is relatively inactive. The reaction involves electron transfer in which cobalt ions function as chain carriers. [Pg.99]

A steady flow of metabolites both in and out of the mitochondrial matrix space is necessary for mitochondria to perform functions which involve the participation of enzymes inside the membrane permeability barrier. These functions include oxidative phosphorylation and therefore O2, ADP, phosphate and electron-rich substrates such as pyruvate, fatty acids and ketone bodies must enter the mitochondria, and the products, HjO, CO2 and ATP must leave. Although Oj, HjO and CO2 are permeable to the inner mitochondrial membrane [1,2], most metabolites are not, because of their highly hydrophiUc nature. The outer mitochondrial membrane does not present a significant barrier to hydrophilic metabolites because of the presence of large unregulated channels composed of the membrane protein, porin [3]. The inner mitochondrial membrane has a much larger surface area [4] than the outer membrane and a much higher ratio of protein to lipid [5]. It is composed not only of proteins involved in electron transport and oxidative phosphorylation but also specialized proteins which facilitate, and in many cases provide, directionality to the transport of metabolites [6]. [Pg.221]

Oxidations of unsaturated ketones affecting solely the carbonyl group were discussed in the section Baeyer-Villiger Reaction of Functionalized Ketones (equations 379-399). In this section, only such oxidations that add oxygen to the double bond will be described. [Pg.212]

The antiviral marine natural product, (-)-hennoxazole A, was synthesized in the laboratory of F. Yokokawa." The highly functionalized tetrahydropyranyl ring moiety was prepared by the sequence of a Mukaiyama aldol reaction, cheiation-controiied 1,3-syn reduction, Wacker oxidation, and an acid catalyzed intramolecular ketalization. The terminal olefin functionality was oxidized by the modified Wacker oxidation, which utilized Cu(OAc)2 as a co-oxidant. Interestingly, a similar terminal alkene substrate, which had an oxazole moiety, failed to undergo oxidation to the corresponding methyl ketone under a variety of conditions. [Pg.475]

Keywords. 3-Functionalized ketones, a-Keto acid derivatives. Cinchona modified Pt catalysts. Chiral imprints. Chiral metal surfaces. Chiral polymers. Cyanohydrin formation. Cyclic Dipeptides, Epoxidation catalysts. Heterogeneous catalysts. Hydrogenation catalysts. Modified metal oxides. Polypeptides, Tartrate-modified Nickel catalysts... [Pg.1274]

The synthesis of the fluoroketone that combines the retroamide type bond (76) is shown in Scheme 5. The 2,2-difluoro-3-hydroxyester 11 from a Reformatsky reaction was converted to the primary amide 12 by treatment with ammonia in diethyl ether. Reduction of the amide with borane dimethyl sulfide and protection of the resulting amine gave the protected intermediate 13. For the preparation of peptides XIV and XV, the hydroxy function was oxidized to the corresponding ketone using pyridinium dichromate. [Pg.167]

A novel method for the introduction of a 3-aryl substituent into a cyclohexanone has been reported.63 This route uses the photocyclization of the thio-aryl compounds (90) to the cyclic products (91), which can be desulphurized by Raney nickel. This treatment partially reduces the carbonyl function but oxidation of the crude product affords high yields of the ketones (92). The mr triplet excited state is responsible for the transformation of 3-anilino-6-methyI-cyclohex-2-en-1 -one into 3,4-dihydro-5-hydroxy-4-methyl-1 -benzazocine.64... [Pg.261]

Oxidation of Carbon Skeletons with IBX. Allylic and benzylic positions are also susceptible to oxidation by IBX. These applications are not limited to the oxidation of compounds containing a pre-existing oxygen functionality but oxidize the hydrocarbon center directly to aldehydes or ketones. These oxidations also proceed via a single-electron-transfer pathway. The oxidation of aryl methyl groups to aryl aldehydes is accomplished with 3 equiv of IBX in DMSO or DMSO/fluorobenzene mixtures at 80-90 The first two equivalents of IBX initiate the single-electron-transfer to generate a benzylic carbocation. Subsequently, the reaction with water affords the alcohol in situ and the third equivalent of IBX completes the conversion to the desired benzaldehyde (eq 13). ... [Pg.208]

The oxidation of midecamycin with dimethyl sulphoxide-acetic anhydride has been studied the macrolide allylic alcohol function was oxidized to the corresponding ketone, whereas the 2 -hydroxy-group on the mycaminose moiety was acetylated rather than oxidized, while the mycarose unit was simultaneously converted to its 3"-0-methylthiomethyl ether derivative. ... [Pg.159]

Unlike the situation with the asterriquinones, a modular synthesis of illudins had already been developed through the efforts of Padwaand Kinder. The dipolar cycloaddition of a carbonyl yhde derived from a diazo-p-diketone with a cyclopentenone forms two C-C bonds and establishes the ring skeleton (Figure 9.7) in the key intermediate. The final carbon was added by a methyl Grignard addition to the more reactive ketone. Oxidation states and functional groups were adjusted to provide dehydroiUudin M, and it was converted to illudin M. [Pg.219]

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