Palladium-catalyzed reactions ketones

Epoxides are normally hydrogenated in preference to saturated ketones but double bonds are usually reduced under these conditions. It is possible in some cases to selectively cleave an epoxide without saturating double bonds by the use of the deactivated catalysts recommended for the partial reduction of acetylenes (see section IV) or by the addition of silver nitrate to the palladium-catalyzed reaction mixture. " ... 

Ketones can also be prepared by palladium-catalyzed reactions of boranes or boronic acids with acyl chlorides. Both saturated and aromatic acyl chlorides react with trialkylboranes in the presence of Pd(PPh3)4.233... 

Larock et al. reported the palladium-catalyzed reactions of alkynes and nitriles with 2-iodophenyl group (Equations (116)-(118)).473,473a 473c Ketones and naphthylamines are obtained presumably through the formation of vinylpalladium species followed by their addition to nitriles to afford palladium imine intermediates. 

Hashmi et al. investigated a number of different transition metals for their ability to catalyze reactions of terminal allenyl ketones of type 96. Whereas with Cu(I) [57, 58] the cycloisomerization known from Rh(I) and Ag(I) was observed (in fact the first observation that copper is also active for cycloisomerizations of allenes), with different sources of Pd(II) the dimer 97 was observed (Scheme 15.25). Under optimized conditions, 97 was the major product. Numerous substituents are tolerated, among them even groups that are known to react also in palladium-catalyzed reactions. Examples of these groups are aryl halides (including iodides ), terminal alkynes, 1,6-diynes, 1,6-enynes and other allenes such as allenylcarbinols. This che-moselectivity might be explained by the mild reaction conditions. 

The mechanism of the Zn chloride-assisted, palladium-catalyzed reaction of allyl acetate (456) with carbonyl compounds (457) has been proposed [434]. The reaction involves electroreduction of a Pd(II) complex to a Pd(0) complex, oxidative addition of the allyl acetate to the Pd(0) complex, and Zn(II)/Pd(II) transmetallation leading to an allylzinc reagent, which would react with (457) to give homoallyl alcohols (458) and (459) (Scheme 157). Substituted -lactones are electrosynthesized by the Reformatsky reaction of ketones and ethyl a-bromobutyrate, using a sacrificial Zn anode in 35 92% yield [542]. The effect of cathode materials involving Zn, C, Pt, Ni, and so on, has been investigated for the electrochemical allylation of acetone [543]. 

The Cope rearrangement of 24 gives 2,6,10-undecatrienyldimethylamine[28], Sativene (25j[29] and diquinane (26) have been synthesized by applying three different palladium-catalyzed reactions [oxidative cyclization of the 1,5-diene with Pd(OAc)2, intramolecular allylation of a /i-keto ester with allylic carbonate, and oxidation of terminal alkene to methyl ketone] using allyloctadienyl-dimethylamine (24) as a building block[30]. 

Azoles can be produced from products of palladium-catalyzed hydrazone arylation and can serve as substrates for arylation reactions to produce N-aryl azoles. The Fischer indole synthesis uses N-ary I hydrazones, and these hydrazones can be generated by palladium-catalyzed chemistry. Benzophenone hydrazone was found by both the Yale and MIT groups to be a particularly effective substrate for palladium-catalyzed reactions, as summarized in Eq. (24) [140,141]. Reactions of benzophenone hydrazone with either aryl bromides or iodides occur in high yields using either DPPF- or BINAP-ligated palladium. These reactions are general and occur with electron-rich, electron-poor, hindered or unhindered aryl halides. The products of these reactions can be converted to hydrazones that bear enolizable hydrogens and are suitable for indole synthesis in the presence of acid and ketone [140]. 

Ketone synthesis. Ketones can be prepared, generally in high yield, by a palladium-catalyzed reaction of acid chlorides with dialk>lzinc compounds, prepared in situ by... 

Dicarbonyl compounds can be prepared by the reactitHi of kemnes with 3-butenyl halide as a Q component, following oxidation of the terminal double bond. A modified method for 3-butenylation of ketones by the palladium-catalyzed reaction of 4-acetoxy-2-butenylmethyl carbonate with ketones, followed by the palladium-catalyzed reaction of ammoiuum formate was reported (Scheme 15). ... 

Logue MW, Teng K (1982) Palladium-catalyzed reactions of acyl chlorides with (l-alkynyl)tributylstannanes. A convenient synthesis for 1-alkynyl ketones. J Org Chem 47 2549-2553... 

A new synthetic method for steroids has been developed using a butadiene dimer (66) as a building block and the palladium-catalyzed oxidation as the key reaction.3-Acetoxy-l,7-octadiene (66), prepared by the palladium-catalyzed reaction of butadiene with acetic acid, is hydrolyzed and oxidized to l,7-octadien-3-one (67) in high yield. The enone (67) is a very useful reagent for bisanellation because its termiiud double bond can be regarded as a masked ketone which can be readily unmasked by the palladium catalyst to form the l,S-diketone (68) after Michael addition at the enone moiety of (67 Scheme 20). Thus, the enone (67) is the cheapest and most readily available bisanellation reagent, permitting a simple total synthesis of steroids. 

This methodology has been used to provide efficient protocols for the asymmetric allylic alkylation of p-keto esters, ketone enolates, barbituric acid derivatives, and nitroalkanes. Several natural products and analogs have been accessed using asymmetric desymmetrization of substrates with carbon nucleophiles. The palladium-catalyzed reaction of a dibenzoate with a sulfonylsuccinimide gave an advanced intermediate in the synthesis of L-showdomycin (eq 3). ... 

General palladium-catalyzed reactions of 1,3-dienes with aldehydes give tetrahy-dropyran derivatives and/or open-chain homoallyl alcohols [61], Thus, the present reaction offers a novel method for preparing /3,y-unsaturated ketones from readily available 1,3-dienes and aldehydes. 

In 2000 Kang and colleagues described the carbonylative coupling of triary-lantimony(V) diacetates and dichlorides in the palladium-catalyzed reaction with organostannanes [59]. Diaryl ketones were produced in good yields using 5 mol % of PdCla in CH3CN at room temperature (Scheme 4.30). 

The first carbonylative coupling of organoaluminum compounds appeared in 1985. Beletskaya and colleagues [88] demonstrated that ketones are produced in good yields by a palladium-catalyzed reaction of arylaluminium compounds with aryl iodides in the presence of CO (Scheme 4.49). That same year, the... 

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