Enamines, telomerization with butadiene

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 results obtained from subsequent studies indicate that this same approach can be used to promote telomerization of butadiene with p-dicarbonyl compounds, nitroalkanes, and enamines. ... 

Butadiene telomerizes with chiral cyclohexanone-derived enamines under substrate control with (5)-2-(methoxymethyl)pyrrolidine (SMP) or its a,a-dimethyl analog as chiral auxiliary12. After removal of the auxiliary by hydrolysis, 2-[( )-2,7-octadienyl]cyclohexanone (6) is obtained in 57 % yield with 72 % ee (R = H) or in 60 % yield with 92 % ee (R = CH3). Cyclopen-tanones, cycloheptanones and cyclooctanones can be similarly converted. 

TelomerizatiorL Conj ugated dienes combine with nucleophiles such as water, amines, alcohols, enamines and stabilized carban-ions in the presence of palladium acetate and triphenylphosphine to produce dimers with incorporation of one equivalent of the nucleophile. Telomerization of butadiene (eq 7) yields linear 1,6- and 1,7-dienes and has been used for the synthesis of a variety of naturally occurring materials. ... 

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See also in sourсe #XX -- [ ]

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