Aryl ketones, synthesis

The precise nature of the carbonyl groups determines what happens next. If R is a leaving group (OR, Cl, etc.), the tetrahedral intermediate collapses to form a ketone and the product is a 1,3-di-ketone. The synthesis of dimedone (later in this chapter) is an example of this process where an alkoxy group is the leaving group. Alternatively, if R is an alkyl or aryl group, loss of R is not an option and the cyclization is an intramolecular aldol reaction, Dehydration produces an a,P-unsaturated ketone, which is a stable final product. 

N. Shibuya and R.S. Porter, Kinetics of PEEK sulfonation in concentrated sulfuric acid, Macromolecules, 1992, 25, 6495-6499 F. Wang and J. Rovers, Functionalization of poly(aryl ether ether ketone) (PEEK) Synthesis and properties of aldehyde and carboxylic acid substituted PEEK, Macromolecules, 1993, 26, 5295-5302. 

DTBNpP and palladium(II) acetate provided an efficient catalytic system for the a-arylation of ketones. Aryl bromides were coupled with ketones using 0.25-0.5 mol% Pd(OAc)2/DTBNpP in toluene at 50 °C. Coupling of 2-bromophenol with ketones using the Pd/DTBNpP system provided an efficient route for the synthesis ofbenzo[f>]furans (14EJ07395). 

Asa contrast, the Mizoroki-Heck reaction in molten salts using ligandless reaction conditions produced the isomerized -arylated ketones. Aryl iodides were first studied, but it was soon shown that aryl bromides were reactive at higher reaction temperatures as well. Lower amounts of catalyst resulted in longer reaction times. The example in Figure 3.30 illustrates a single-step synthesis of the nonsteroidal anti-inflammatory drug Nabumethone [90]. 

Keywords High performance pol)rmer, poly (aryl ether ketone), copolymers, synthesis, characterization... 

The abihty to perform oxidations without generating species harmful for potential intermediates of further transformations is important to perform multistep synthesis, such as the domino reactions described below (Section 5). In this respect, the use of aryl hahdes as readily available, stable and cheap oxidants (hydride acceptors) is a powerful option due to the production of inert, dehalogenated aryl by-products in anaerobic conditions. Commercially available Pd and Ni complexes with NHC ligands were found to be active in a temperature-controlled domino oxidation/R-ketone arylation with aryl halide. ... 

The synthesis will therefore normally produce a 2,4-substituted pyrrole, with in addition an ester group or an acyl group at the 3-position, if a keto ster or a diketone respectively has been employed, and an ester group or an alkyl (aryl) group at the 5-position, according to the nature of the amino-ketone. 

Organotin compounds such as aryl-, alkenyl-, and alkynylstannanes are useful for the ketone synthesis by transmetallation of acylpalladium 529 and reductive elimination of 530 as shown[389-393]. Acetophenone (531) is obtained by the carbonylation of iodobenzene with Me4Sn. Diaryl ketones... 

Synthesis and Properties. Polyquinolines are formed by the step-growth polymerization of o-aminophenyl (aryl) ketone monomers and ketone monomers with alpha hydrogens (mosdy acetophenone derivatives). Both AA—BB and AB-type polyquinolines are known as well as a number of copolymers. Polyquinolines have often been prepared by the Friedlander reaction (88), which involves either an acid- or a base-catalyzed condensation of an (9-amino aromatic aldehyde or ketone with a ketomethylene compound, producing quinoline. Surveys of monomers and their syntheses and properties have beenpubhshed (89—91). 

The wide variety of ketomethylene and amino ketone monomers that could be synthesized, and the abiUty of the quinoline-forming reaction to generate high molar mass polymers under relatively mild conditions, allow the synthesis of a series of polyquinolines with a wide stmctural variety. Thus polyquinolines with a range of chain stiffness from a semirigid chain to rod-like macromolecules have been synthesized. Polyquinolines are most often prepared by solution polymerization of bis(i9-amino aryl ketone) and bis (ketomethylene) monomers, where R = H or C H, in y -cresol with di-y -cresyl phosphate at 135—140°C for a period of 24—48 h (92). 

Another synthesis of the cortisol side chain from a C17-keto-steroid is shown in Figure 20. Treatment of a C3-protected steroid 3,3-ethanedyidimercapto-androst-4-ene-ll,17-dione [112743-82-5] (144) with a tnhaloacetate, 2inc, and a Lewis acid produces (145). Addition of a phenol and potassium carbonate to (145) in refluxing butanone yields the aryl vinyl ether (146). Concomitant reduction of the C20-ester and the Cll-ketone of (146) with lithium aluminum hydride forms (147). Deprotection of the C3-thioketal, followed by treatment of (148) with y /(7-chlotopetben2oic acid, produces epoxide (149). Hydrolysis of (149) under acidic conditions yields cortisol (29) (181). 

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