4.6- Heptadienoic acid sodium salt

Under analogous aqueous reaction conditions, the sodium salts of ( )-3,S-hexadienoic, ( , )-6-meth-oxy-3,5-hexadienoic and ( )-4,6-heptadienoic acid underwent high-yielding [4 + 2] cycloadditions to a variety of dienophiles, e.g. to the Ca-substituted enal (248) (Scheme 58). The crude Diels-Alder... 

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