Dienamines with methyl acrylate

A similar [4 + 2] cycloaddition across the a, -positions has been observed in the reaction of isophorone dienamines with electrophilic alkenes (vide infra), and a similar ring opening has been postulated in the reaction of methyl vinyl ketone with dienamines in aprotic media (Section VII.C). Confirmatory evidence for the role of the C-3 methyl group in the above reaction was obtained from reaction of 8-methyl-A 1,8a-2-octalone dienamine with methyl acrylate only the /Talkylated product was obtained in protic and aprotic solvents14. The reaction of dienamines with electrophilic alkenes is discussed further in the section on carbocyclic synthesis (Section VII.C). 

Similar adducts are formed when the dienamine is allowed to react with methyl vinyl ketone and with methyl acrylate. 

Similarly, Birch reduction products 17 and 18 react with acrylonitrile to give a,(5 -cycloadduct 19 derived from the linear dienamine, but with methyl acrylate to give / , y-cycloadduct 20 and -alkylation product 21 (after hydrolysis) derived from the cross-conjugated dienamine35 (Scheme 20). 

Enamines have been observed to act both as dienophiles (46-48) and dienes (47,49) (dienamines in this case) in one-step, Diels-Alder type of 1,4 cycloadditions with acrylate esters and their vinylogs. This is illustrated by the reaction between l-(N-pyrrolidino)cyclohexene (34) and methyl t/-a i-2,4-pentadienoate (35), where the enamine acts as the dienophile to give the adduct 36 (47). In a competitive type of reaction, however, the... 

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