Butadiene telomerization with acetic acid

Telomerization Reactions. Butadiene can react readily with a number of chain-transfer agents to undergo telomerization reactions. The more often studied reagents are carbon dioxide (167—178), water (179—181), ammonia (182), alcohols (183—185), amines (186), acetic acid (187), water and CO2 (188), ammonia and CO2 (189), epoxide and CO2 (190), mercaptans (191), and other systems (171). These reactions have been widely studied and used in making unsaturated lactones, alcohols, amines, ethers, esters, and many other compounds. 

Few studies have been carried out on the telomerization of carboxylic acids other than acetic acid. Carboxylic acids are expected to react similarly with butadiene. The exception is formic acid No telomerization takes place, as described before (33, 34), and it behaves as a reductant rather than a nucleophile, forming 1,6- and 1,7-octadienes and octatriene. 

Some authors have proposed mechanisms based on bimetallic palladium species. Keim and colleagues, for instance, proposed a reaction mechanism for the telomerization of acetic acid with butadiene (Scheme 10), where the key intermediate is a bispalladium compound such as Pd2([i-1,2,3,6,7,8-r 6-octa-2,7-dien-l, 8-diyl)((j,-OAc)2] [65]. It was shown that these bimetallic compounds are able to catalyse telomerization in the presence of 1,3-butadiene, acetic acid and a phosphine ligand. 

The telomerization reaction of acetic acid and 1,3-butadiene yielding acetoxyoctadienes with an (Tj -allyOpalladium acetate dimer was studied and a reaction mechanism proposed which was based on the key interme-... 

Tsuji has completed three syntheses of zearalenone (119), all by quite similar routes. The first, shown in Scheme 1.28, began with acetate 59b, the minor product from the telomerization of butadiene in acetic acid. Cleavage to the alcohol and gas-phase dehydrogenation led to enone 141. Chain extension to 142 was accomplished in 70% yield by way of Michael addition of diethyl malonate to enone 141. Decarboalkoxylation and protection of the ketone then gave 143 (63%). Conversion of the ester to the primary tosylate 144 was achieved by conventional methods in 62% yield. A Wacker oxidation of the terminal olefin followed by reduction and exchange of the tosylate for an iodide then provided the aliphatic segment 145 in 64% yield. 

Palladium(I) intermediates have been proposed for the telomerization of butadiene with acetic acid yielding acetoxyoctadienes, and in a recent review the involvement of Pd(I) has been snggested for processes in which Pd(II) had been formerly suggested. These processes include alkene isomerization, methoxycarbonylation of alkynes to acrylic esters, and the aryloxycarbonylation of allyl alcohol. 

Full details of the Ni - and Pd -catalysed telomerization reactions of butadiene with phenylhydrazones (see Volume 6, p. 388) have now been published. Reaction of butadiene with diethylamine gives (49 Z = NEta) in the presence of allyl M halides. The catalytic activity increases in the series M = Ni < M = Ptsimilar reactions of butadiene, especially virith cyclic secondary amines (e.g. morpholine). For M = Pd addition of AcOH improves the yield of (49 Z = NEta) whilst for M = Pt no telomers are formed in the absence of Al(OR)3 (R = Pr or Bu ) co-catalysts. The reaction of butadiene with acetic acid to give (49 Z = OAc) is also catalysed by [M(cod)2] although with the catalyst M = Pd l-vinylhex-5-enyl acetate is a by-product (20%). Reactions of butadiene with acetaldehyde and phenyl isocyanate in the presence of [Pd(cod)t]-2PPh3 give (50 and (51), respectively, ... 

Heterogenized Catalysts.—Telomerization of butadiene with acetic acid gives the same ratio of 1 1 and 2 1 adducts whether catalysed by Pd(OAc)a-PPh3... 

In what follows, the telomerization of butadiene with acetic acid, alcohols, phenol, C—H-acidic compounds and nitroalkanes will be considered. Also some examples of carboxytelomerization and the telomerization of substituted dienes will be given. In all reactions trifunctional compounds are formed which contain two double bonds and one functional group. 

To prepare more hydrophobic starches for specific applications, the partial substitution of starch with acetate, hydroxypropyl, alkylsiliconate or fatty-acid ester groups has been described in the literature. A new route, however, consists of grafting octadienyl chains by butadiene telomerization (Scheme 3.9) [79, 82, 83], The reaction was catalyzed by hydrosoluble palladium-catalytic systems prepared from palladium diacetate and trisodium tris(m-sulfonatophenyl)phosphine (TPPTS). 

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