Ketone aryl chlorides

Sulfur tetrafluoride [7783-60-0] SF, replaces halogen in haloalkanes, haloalkenes, and aryl chlorides, but is only effective (even at elevated temperatures) in the presence of a Lewis acid catalyst. The reagent is most often used in the replacement of carbonyl oxygen with fluorine (15,16). Aldehydes and ketones react readily, particularly if no alpha-hydrogen atoms are present (eg, benzal fluoride [455-31-2] from benzaldehyde), but acids, esters, acid chlorides, and anhydrides are very sluggish. However, these reactions can be catalyzed by Lewis acids (HP, BF, etc). 

The push-spectator stabilization system enables one to employ various alkyl groups with different types of steric environment, which differentiate amino(alkyl) carbenes dramatically from the NHCs as ligands. Taking advantage of their steric and electronic properties, Bertrand et al. nicely demonstrated the utility of CAACs as ligands in the palladium catalyzed a-arylation of ketones. Depending on the nature of the aryl chloride used, dramatic differences were observed in the catalytic activity of Pd-complexes with CAACs featuring different types of steric environment [36]. 

FRIEDEL-CRAFTS REACTION. Aluminum chloride anhydrous, introduced by Friedcl and Crafts, is used as reagent, generally in CS solution to avoid rise in temperature, for the preparation of (I) aryl-alkyl hydrocarbons, (2) di- and triphenylmethane and derivatives, and (3) aryl-alkyl and diaryl ketones, Other chlorides, such as those of zinc, irun(lll), and liniiV), are often effective in certain cases. 

The above data which are presented in Tables I-IV show that the diphosphine complexes are effective catalysts for the aldehyde decarbonylation. Although these reactions tolerate various functional groups such as carboxylic acids, ethers, ketones, olefins, and aryl chlorides,... 

Ester, nitrile, or ketone functions are tolerated in the method. Aryl chlorides can be applied with only slightly decreased yields. For 3-bromopropionate the bipyridine ligand was mandatory for the success of the reaction. The involvement of radicals is supported by ring opening occurring when cyclopropylmethyl bromide was used as the substrate (cf. Part 1, Fig. 8). 

Phenols are transformed into aryl chlorides by PhPCl4779. Aromatic and aliphatic aldehydes give, in high yields, gem dibromides with combination of triphenylphosphite and bromine780. Brominative deoxygenation of ketones is achieved by 2,2,2-tribromo-l,2,3-benzodioxaphosphone781. Allylic alcohols are transformed into allylic iodides by reaction with P2I4782. 

The cross-coupling of aryl halides and enolates is a powerful method to prepare a-arylated carbonyl compounds that are difficult to access through classic organic chemistry [29]. (NHC)Pd(allyl)Cl species [30] were the first NHC-bearing complexes used as pre-catalysts for the a-arylation of ketones [31,32]. More recently, novel (IPr)Pd(acac)Cl complexes have shown remarkable catalytic activity in this transformation [33]. From aryl chlorides, excellent yields were obtained after short reaction times at 60 °C, the lowest temperature reported to date with a carbene-based system (Table 1). 

Alkenyl, Alkynyl, Aryl and Related Acids. Vinylphosphonates are an important group of compounds that have found use in organic transformations. They are also useful reagents for the synthesis of biologically active systems. The synthesis of vinylphosphonates is varied. However additional convenient routes to them are always welcome. Four recent reports demonstrated that zirco-nacycles (180), readily available from diethyl 1-alkynylphosphonates, are very useful precursors of different vinylphosphonates. They react with alkynes, aldehydes, ketones acyl chlorides and nitriles to produce, in a highly stereo- and regio-selective manner, substituted vinylphosphonates (181), (182), (183) (184) and (185) respectively (Scheme 46). 

Primary, secondary, and tertiary alkyl chlorides as well as aryl chlorides undergo reductive dechlorination using Sml2, and in the presence of CO ketones are formed by photocarbonylation. ° ... 

Titanocene dichloride catalyzes the reduction of alkyl, aryl, and vinyl bromides, aryl chlorides, alkoxy- and halosilanes ketones, esters, and carboxylic acids with alkyl Grignard reagents. This Cp2TiCl2/RMgX system can also be used for the hydromagnesation of alkynes, dienes, and alkenes (Section 3.2.5). Kambe et al. have reported a new type of titanocene-catalyzed transformation with vinyl Grignard reagents and chlorosilanes to furnish l,4-disilyl-2-butenes, as shown in Scheme 3.43 [31]. 

Complex 7 was tested for a-ketone arylation reactions (Table 14.9) and Bnchwald-Hartwig ami-nation reactions with activated and unactivated aryl chlorides (Table 14.10). In both cases, very good results were obtained using mild temperatures in short reaction times. 

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