Ketones palladium acetate

Diazonium salts react with oximes to give aryl oximes, which are easily hydrolyzed to aldehydes (R = H) or ketones." A copper sulfate-sodium sulfite catalyst is essential. In most cases higher yields (40-60%) are obtained when the reaction is used for aldehydes than for ketones. In another method for achieving the conversion ArNj —> ArCOR, diazonium salts are treated with R4Sn and CO with palladium acetate as catalyst. In a different kind of reaction, silyl enol ethers of aryl ketones, Ar C(OSiMe3)=CHR, react with sohd diazonium fluoroborates, ArNj BF4, to give ketones, ArCHRCOAr. " This is, in effect, an arylation of the aryl ketone. 

Enantioselective deprotonation can also be successfully extended to 4,4-disubstituted cyclohexanones. 4-Methyl-4-phenylcyclohexanone (3) gives, upon reaction with various chiral lithium amides in THF under internal quenching with chlorotrimethylsilane, the silyl enol ether 4 having a quaternary stereogenic carbon atom. Not surprisingly, enantioselectivities are lower than in the case of 4-tm-butylcyclohexanone. Oxidation of 4 with palladium acetate furnishes the a./i-unsaturated ketone 5 whose ee value can be determined by HPLC using the chiral column Chiralcel OJ (Diacel Chemical Industries, Ltd.)59c... 

METHYL KETONES AUyltrimethyl-silane, Bis(acetonitrilo)chloronitro-palladium (11). Dicarb ony lbis( triphenyl-phosphine)nickel. Dichloro-dicyano-benzoquinone. Hydrogen peroxide-Palladium acetate. Meldrum s acid. Palladium r-butyl peroxide trilluoro-acctate. Palladium tl) chloride. 

Ketones from halohydrins. Palladium acetate complexed with a triarylphos-phine, particularly tri-o-tolylphosphine, converts halohydrins into ketones in the presence of K2C03. Yields are about 70-85% for substrates in which the halogen is secondary or tertiary, but less than 50% when the halogen is primary because of epoxide formation. The reaction is useful for conversion of alkenes to ketones in those instances in which halohydrins are formed regioselectively. 

The palladium acetate addition to 1-olefins in acetic acid solution is predominately of the Markovnikov type producing ketone enol esters 14>. 

The ring expansion of the benzoxepinones 134 to benzoxocinones 136 involved a cyclopropanation with diazomethane in the presence of palladium acetate and a catalytic hydrogenation. The cleavage of the more labile internal bond in the cyclopropyl derivatives 135 leads to the eight-membered ketones 136 exclusively in excellent yields (90-95%). Reduction of ketones 136 with sodium borohydride affords the hydroxy derivatives 137 in a stereo-controlled manner (Scheme 34) <2002CC634>. 

An exception involves the passage of hot alcohol vapors over thorium oxide at 350-450°C, under which conditions Hofmann s mle is followed, and the mechanism is probably different. Cyclobutanol derivatives can be opened in the presence of a palladium catalyst. 2-Phenylbicyclo[3.2.0]octan-2-ol, for example, reacted with a catalytic amount of palladium acetate in the presence of pyridine and oxygen to give phenyl methylenecyclohexane ketone. ... 

Conversion of acyl halides to aromatic ketones using triphenylbismuthine and palladium acetate general procedure... 

To a stirred suspension of palladium acetate (0.05 mmol) in HMPA (1 ml) was added triethy-lamine (0.1 mmol) at room temperature under argon. A yellow solution resulted within 2-3 min, to which a solution of an appropriate acid chloride (5 mmol) in HMPA (2 ml) followed by triphenylbismuthine (1 mmol) in the same solvent (5 ml) was introduced slowly. The reaction mixture was heated at 65°C for 5 h, then cooled, diluted with ether (50 ml) and filtered through a short column of basic alumina. The column was washed with ether (4 X 25 ml) and the combined ethereal washings were shaken with water (3 X 250 ml). The organic phase was separated, dried over anhydrous magnesium sulfate and evaporated to give the expected ketone, which was further purified either by preparative TLC or by recrystallization [88T5661]. 

Palladium catalysts are widely used in liquid phase aerobic oxidations, and numerous examples have been employed for large-scale chemical production (Scheme 8.1). Several industrially important examples are the focus ofdedicated chapters in this book Wacker and Wacker-type oxidation of alkenes into aldehydes, ketones, and acetals (Scheme 8.1a Chapters 9 and 11), 1,4-diacetoxylation of 1,3-butadiene (Scheme 8.1b Chapter 10), and oxidative esterification of methacrolein to methyl methacrylate (Scheme 8.1c Chapter 13). In this introductory chapter, we survey a number of other Pd-catalyzed oxidation reactions that have industrial significance, including acetoxylation of ethylene to vinyl acetate (Scheme 8. Id), oxidative carbonylation of alcohols to dialkyl oxalates and carbonates (Scheme 8.1e), and oxidative coupling of dimethyl phthalate to 3,3, 4,4 -tetramethyl biphenylcarboxy-late (Scheme 8.1f). 

The same transformations can he effected by reaction of the trialkylsilyl enol ether of the aldehydes or ketones with palladium acetate. For example, treatment of the trimethylsilyl enol ether of cyclooctanone with 10 mol% Pd(OAc)2 in DMSO under one atmosphere of oxygen at 25 °C for 12 h gave cyclooctenone (82% yield). 

The first attempts to use transition metal-catalyzed cross-coupling methodology to couple enolates with aryl halides were far from being broadly applicable, and involved less-attractive preformed zinc- or tin-enolates [210]. In addition, only ketones or acetates could be employed as enolate precursors. At that time, nickel was the predominant transition metal to mediate these couplings [211]. In an early contribution, CiufoHni arylated soft enolates in an intramolecular fashion with aryl halides using Pd(PPh3)4, along with NaH, in DMF at elevated temperatures [212]. This represented one of the first palladium-catalyzed arylations of enolates. 

Two slightly different methodologies have been reported for the use of catalytic palladium acetate in the oxidation of alcohols, which interestingly give quite different selectivities. Thus, when iodobenzene is used as re-oxidant in a buffered phase transfer system modest to quantitative gas chromatographic yields of aldehydes or ketones are obtained from... 

Condensations between ethyl isocyanoacetate and unsaturated aldehyde (or ketones) in the presence of ZnCl2 or CuCl-Et N lead to oxazolines (522) in variable yields (29-95%). " Subsequent treatment with 2.5 mol% of palladium acetate and PPh (THF, 20 °C) gives excellent yields of the formamido-dienoates (523). The mechanism probably involves initial oxidative addition of the... 

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