Ethylene acylation

Examples of the oxidative reactions of olefins with carboxylic acids are shown in Equations 16.107-16.109. These examples illustrate the selectivities of the oxidations of ethylene, acylic alkenes, and cyclic alkenes. The reactions of alkenes with carboxylic adds generate either vinylic esters or allylic esters. 

The scope of the functionalization reaction can be widespread to other 0, j(3-ethylenic acyl chlorides. 

The possibility of a cyclization by condensation of o ,jS-ethylenic acyl chlorides with l,8-bis(trimethylsilyl) 2,6-octadiene in the presence of a Lewis acid came to our attention. In this way, the intermediate, j8-ethylenic ketone could... 

Acylation of disilyloctadiene U with ethylenic acyl chlorides led only to cyclopentyl ketones. 

Ethylene acylation is currently used in one step of the classical Roussel-UCLAF s synthesis of steroids. See Velluz, J. Nomine, G. Amiard, G. Torelli, V. Cerede, J. C.R. Acad. Sci. Paris 1963, 257, 3086. 

Although allylic silanes fail to react with a,/3-ethylenic esters, conjugate addition to a,/3-ethylenic acyl cyanides occurs quantitatively under the influence of titanium tetrachloride to give 5,e-ethylenic acyl cyanides, acids, or esters, depending on the work-up procedure (e.g. Scheme 68)/ Allenic silanes react in an analogous way to give the corresponding 5,e-acetylenic compounds. 

Z)-Ethylenic mixed anhydrides are easily prepared without isomerization and react with vinyl cuprates (and other organometallics) under Pd° catalysis with >99% stereochemical control to give unsymmetrical divinyl ketones (eq 18). Alternative routes via (Z)-ethylenic acyl chlorides produce ( /Z) mixtures. 

Another important use of BCl is as a Ftiedel-Crafts catalyst ia various polymerisation, alkylation, and acylation reactions, and ia other organic syntheses (see Friedel-Crafts reaction). Examples include conversion of cyclophosphasenes to polymers (81,82) polymerisation of olefins such as ethylene (75,83—88) graft polymerisation of vinyl chloride and isobutylene (89) stereospecific polymerisation of propylene (90) copolymerisation of isobutylene and styrene (91,92), and other unsaturated aromatics with maleic anhydride (93) polymerisation of norhornene (94), butadiene (95) preparation of electrically conducting epoxy resins (96), and polymers containing B and N (97) and selective demethylation of methoxy groups ortho to OH groups (98). 

Boron Bromide. Approximately 30% of BBr produced in the United States is consumed in the manufacture of proprietory pharmaceuticals (qv) (7). BBr is used in the manufacture of isotopicaHy enriched crystalline boron, as a Etiedel-Crafts catalyst in various polymerization, alkylation, and acylation reactions, and in semiconductor doping and etching. Examples of use of BBr as a catalyst include copolymerization of butadiene with olefins (112) polymerization of ethylene and propylene (113), and A/-vinylcarbazole (114) in hydroboration reactions and in tritium labeling of steroids and aryl rings (5). 

Acetal Resins. Acetal resins (qv) are poly (methylene oxide) or polyformaldehyde homopolymers and formaldehyde [50-00-0] copolymeri2ed with ahphatic oxides such as ethylene oxide (42). The homopolymer resin polyoxymethylene [9002-81-7] (POM) is produced by the anionic catalytic polymeri2ation of formaldehyde. For thermal stabiUty, the resin is endcapped with an acyl or alkyl function. 

Acyl halides may also be added to ethylene ia the presence of aluminum chloride to form halogenated ketones. At low temperatures, ethylene reacts with halogens to yield dihaloethanes. At high temperatures, trichloroethylene and perchloroethylene are formed. The most profitable route for chloroethylene is via ethylene dichloride (see Chlorocarbonsandchlorohydrocarbons). 

With Acyl Halides, Hydrogen Halides, and Metallic Halides. Ethylene oxide reacts with acetyl chloride at slightly elevated temperatures in the presence of hydrogen chloride to give the acetate of ethylene chlorohydrin (70). Hydrogen haUdes react to form the corresponding halohydrins (71). Aqueous solutions of ethylene oxide and a metallic haUde can result in the precipitation of the metal hydroxide (72,73). The haUdes of aluminum, chromium, iron, thorium, and zinc in dilute solution react with ethylene oxide to form sols or gels of the metal oxide hydrates and ethylene halohydrin (74). 

Conversion of acyl chlorides to lunctlonalized (OH, OCH3, OPh, SCH3) ketones by means ol tns(tnmethylsilyloxy)ethylene 4... 

Acylation of 1,4-dimethoxynaphthalene with acetic anhydride (1.2 equiv) and aluminum chloride (2.2 equiv) in ethylene dichloride (60°C, 3 h) gives two products, 6-acetyl-l,4-dimethoxynaphthalene (30%) and l-hydroxy-2-acetyl-4-methoxynaphtha-lene (50%). Suggest a rationalization for the formation of these two products and, in particular, for the differing site of substitution in the two products. 

Alcoholysis of 1 -chloro-2-acyl-1,1,2-trifluoroethane, available from trifluoro-ethylene, an acyl chloride, and aluminum chloride, leads to 1-fluoro- 1-acylacetates [/] (equation 1) It is surpnsing that the remaining carbon-tluorine bond resists hydrolysis. 

By 0-acylation with 2-methyl-1,3-dioxolenium fluoroborate, which reacts as 0-acetyl ethylene oxide, 2,6-dimethyl-4-pyroiie is converted into 4-acetoxy-2,0-dimethylpyrylium fluoroborate (24, Y = 0, R = Ac, X=BT 4). The alleged compound with this structure which has been obtained from 8 and acetyl fluoroborate is, in fact, the BF3-complex of the pyrone. 

Low yields of 5-acyl-2,3-dihydropyrrolo[2,l-Z ]oxazoles (37) were obtained by treatment of 2-acyl-5-nitropyrrole (35) with ethylene oxide. Better yields are reported starting from hydroxy derivative 36a or its acetate 36b using sodium hydride in THE The presence of an acyl group at the position 2 was found necessary for the cyclization (Scheme 5) (71JCS(C)2554). 

Acylation of norephedrine (56) with the acid chloride from benzoylglycolic acid leads to the amide (57), Reduction with lithium aluminum hydride serves both to reduce the amide to the amine and to remove the protecting group by reduction (58), Cyclization by means of sulfuric acid (probably via the benzylic carbonium ion) affords phenmetrazine (59), In a related process, alkylation of ephedrine itself (60) with ethylene oxide gives the diol, 61, (The secondary nature of the amine in 60 eliminates the complication of dialkylation and thus the need to go through the amide.) Cyclization as above affords phendimetra-zine (62), - Both these agents show activity related to the parent acyclic molecule that is, the agents are CNS stimulants... 

An analogous sequence leads to the anthelmintic agent, etibendazole (50). Reaction of the benzophenone 47, which can be obtained by acylation of o-nitroaniline with g-fluorobenzoyl chloride, with ethylene glycol leads to acetal 48. Sequential reduction of the nitro group and cyclization of the resulting diamine (49) with N,N-dicarbomethoxy-S-methylthiourea gives the benzimidazole etibendazole (50) fl6]. 

Acyl chlorides react with ethylene oxide in the presence of Nal to give 2-iodoethyl esters. 

Reaction of acyl chlorides with ethylene oxide and Nal... 

The square planar Ni11 complex (583) was prepared from the template reaction of 3,3 -(ethylene bis(iminomethylidene)bis(2,4-pentanedionato)nickel(II) with l,3-diamino-2-propanol (Equation (18)). The uncoordinated OH group reacted smoothly with acylating agents, resulting in... 

The stereoselective total synthesis of (+)-epiquinamide 301 has been achieved starting from the amino acid L-allysine ethylene acetal, which was converted into piperidine 298 by standard protocols. Allylation of 297 via an. V-acyliminium ion gave 298, which underwent RCM to provide 299 and the quinolizidine 300, with the wrong stereochemistry at the C-l stereocenter. This was corrected by mesylation of the alcohol, followed by Sn2 reaction with sodium azide to give 301, which, upon saponification of the methyl ester and decarboxylation through the Barton procedure followed by reduction and N-acylation, gave the desired natural product (Scheme 66) <20050L4005>. 

Tributylstannyl)-3-cyclobutene-1,2-diones and 4-methyl-3-(tributylstan-nyl)-3-cyclobutene-l,2-dione 2-ethylene acetals undergo the palladium/copper-catalyzed cross coupling with acyl halides, and palladium-catalyzed carbon-ylative cross coupling with aryl/heteroaryl iodides [45]. The coupling reaction of alkenyl (phenyl )iodonium triflates is also performed by a palladium/copper catalyst [46],... 

Among the wide variety of organic reactions in which zeolites have been employed as catalysts, may be emphasized the transformations of aromatic hydrocarbons of importance in petrochemistry, and in the synthesis of intermediates for pharmaceutical or fragrance products.5 In particular, Friede 1-Crafts acylation and alkylation over zeolites have been widely used for the synthesis of fine chemicals.6 Insights into the mechanism of aromatic acylation over zeolites have been disclosed.7 The production of ethylbenzene from benzene and ethylene, catalyzed by HZSM-5 zeolite and developed by the Mobil-Badger Company, was the first commercialized industrial process for aromatic alkylation over zeolites.8 Other typical examples of zeolite-mediated Friedel-Crafts reactions are the regioselective formation of p-xylene by alkylation of toluene with methanol over HZSM-5,9 or the regioselective p-acylation of toluene with acetic anhydride over HBEA zeolites.10 In both transformations, the p-isomers are obtained in nearly quantitative yield. 

The resulting complexes can be effectively employed as single component catalysts to homopolymerize ethylene or copolymerize ethylene with acrylates [50, 51] and a variety of other polar monomers including vinyl ethers, [51,52] vinyl fluoride [53], iV-vinyl-2-pyrrolidinone, and AMsopropylacrylamide [54], In fact, the resulting catalysts are so robust that they can be used as single component catalysts in aqueous emulsion homo-polymerization of ethylene and copolymerization of ethylene with norbomenes and acylates [55]. 

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