Telomerization reaction amines

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. 

These telomerization reactions of butadiene with nucleophiles are also catalyzed by nickel complexes. For example, amines (18-23), active methylene compounds (23, 24), alcohols (25, 26), and phenol (27) react with butadiene. However, the selectivity and catalytic activity of nickel catalysts are lower than those of palladium catalysts. In addition, a mixture of monomeric and dimeric telomers is usually formed with nickel catalysts ... 

The most characteristic reaction of butadiene catalyzed by palladium catalysts is the dimerization with incorporation of various nucleophiles [Eq. (11)]. The main product of this telomerization reaction is the 8-substituted 1,6-octadiene, 17. Also, 3-substituted 1,7-octadiene, 18, is formed as a minor product. So far, the following nucleophiles are known to react with butadiene to form corresponding telomers water, carboxylic acids, primary and secondary alcohols, phenols, ammonia, primary and secondary amines, enamines, active methylene compounds activated by two electron-attracting groups, and nitroalkanes. Some of these nucleophiles are known to react oxidatively with simple olefins in the presence of Pd2+ salts. Carbon monoxide and hydrosilanes also take part in the telomerization. The telomerization reactions are surveyed based on the classification by the nucleophiles. 

The linear telomerization reaction of dienes was one of the very first processes catalyzed by water soluble phosphine complexes in aqueous media [7,8]. The reaction itself is the dimerization of a diene coupled with a simultaneous nucleophilic addition of HX (water, alcohols, amines, carboxylic acids, active methylene compounds, etc.) (Scheme 7.3). It is catalyzed by nickel- and palladium complexes of which palladium catalysts are substantially more active. In organic solutions [Pd(OAc)2] + PPhs gives the simplest catalyst combination and Ni/IPPTS and Pd/TPPTS were suggested for mnning the telomerizations in aqueous/organic biphasic systems [7]. An aqueous solvent would seem a straightforward choice for telomerization of dienes with water (the so-called hydrodimerization). In fact, the possibility of separation of the products and the catalyst without a need for distillation is a more important reason in this case, too. 

Less attention has been paid to the use of amines as nucleophiles in the telomerization reaction. A single report from Nolan and co-workers [233] has shown that well-defined cationic palladium complexes are efficient catalysts in the telomerization of butadiene with amines under mild conditions (Table 10). In the case of primary amines, the concentration of the reactants and their steric hinderance dictates the formation of a mono- or double-alkylated product. 

The linear telomerization reaction [1] of dienes (the taxogen) with nucleophiles (the telogen) such as alcohols, amines, carboxylic acids, active methylene compounds, phenols, or water provides an elegant method for the synthesis of various useful compounds (Eq. 1). 

The telomerization reaction is carried out using the catalyst modified with amine-containing phosphines, then hydrochloric acid is introduced into the above reaction mixture. As a result phosphine is changed to the hydrochloric acid salt of the amine, so the modified catalyst is dissolved in water. The catalyst can be re-used after treatment with an alkaline solution [2]. 

Telomerization Reactions Involving Amine-Chelated Lithium Catalysts... 

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, ... 

Although acetonitrile is one of the more stable nitriles, it undergoes typical nitrile reactions and is used to produce many types of nitrogen-containing compounds, eg, amides (15), amines (16,17) higher molecular weight mono- and dinitriles (18,19) halogenated nitriles (20) ketones (21) isocyanates (22) heterocycles, eg, pyridines (23), and imidazolines (24). It can be trimerized to. f-trimethyltriazine (25) and has been telomerized with ethylene (26) and copolymerized with a-epoxides (27). 

Similarly, Itexafluoroprapylene undergoes fluoride ion induced homotelo-merization to give a series of dimers and trimers These telomerizations can be induced by other nucleophiles, such as amines Indeed, the selectivity of the pi oce-,s can be changed significantly by varying reagents and reaction conditions [25, 26] (equations 19 and 20)... 

Nielsen DJ, Cavell KJ (2006) Pd-NHC complexes as catalysts in telomerization and aryl amination reactions. In Nolan SP (ed) N-Heterocyclic carbenes in synthesis. WUey-VCH, Weinheim, pp 73-102... 

In an analoguous case, two-phase telomerization of butadiene with ammonia to give octadienylamine has been reported where higher selectivity is realized in a two-phase system of water-toluene. Here, octadienylamine is more reactive than ammonia and consecutive reaction leads to sec and ten amines. By adopting a two-phase strategy, a primary amine selectivity as high as 91 % has been realized (Drieben-Hoscher and Keim, 1998). 

Trialkylamines are used as additives in the telomerization of butadiene and water in a two-phase system (103). The catalyst comprises a palladium salt and tppms or tppts. The amines may build cationic surfactants under catalytic conditions and be capable of micelle formation. The products include up to five telomerization products (alcohols, alkenes, and ethers), and thus the reaction is nonselective. 

Several catalytic systems have been investigated for hydroamination of unsaturated bonds [16]. Takahashi et al. reported the telomerization of 1,3-dienes in the presence of an amine leading to octadienylamine or allylic amines when palladium catalysts are used in association with monodentate or bidentate phosphine ligands, respectively [17]. Dieck et al. demonstrated the beneficial effect of addition of an amine hydroiodic salt in the hydroamination reaction of 1,3-dienes in which the allylic amines are produced via an intermediate Jt-allyl palladium complex [18]. Coulson reported the Pd-catalyzed addition of amines to allenes where dimerization is incorporated [4]. This reaction presumably proceeds via a cyclic palladium intermediate in which the Pd activates the olefinic bond for nucleophilic attack the reactions are therefore different from pronucleophilic additions. 

Palladium-phosphine complexes such as Pd [PPh3 ]4 or, most conveniently, Pd(OAc)2 and PPh3 are used. Usually, these telomers are obtained in high yields. Nucleophiles such as water, carboxylic acids, alcohols, phenols, ammonia, amines, enamines, nitroalkanes, and active methylene and methyne compounds participate in telomerization. Also, carbon monoxide and hydrosilanes are involved in the reaction to give telomers. These easily available telomers are trifunctional and extremely useful starting materials for simple synthesis of certain types of natural products. 

Telomerization of butadiene into 2,7-octadien-l-ol was also performed in neat water in the presence of carbon dioxide and certain trialkylamines in the presence of Pd(OAc)2/tppts or Pd(OAc)2/tppms, the structure of these amines having an important influence on the rate and the selectivity of the reaction... 

During the 1970 s,the lithium diethylamide catalyzed anionic telomerizations of myrcene 4, Eq. (2) [4] and isoprene, Eq. (3) [5] with secondary aliphatic amines were discovered. These reactions are highly chemo- and regioselective and opened the way for the production of various useful terpenoids. The selective formation of N,N-diethylnerylamine 5 from isoprene is noteworthy, because this reaction is only one example hitherto known that can effect isoprene coupling in the natural fashion. 

In the presence of suitable cocatalysts such as alcohols, phenols, or secondary amines, 1,3-diolefins are oligomerized to linear dimers or trimers by the same nickel-ligand systems, which are effective for cyclooligomerization (see 14.5.2.5.1). Reactions may be accompanied by telomerization. Typical examples are given in Table 1. 

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