Palladium-Catalyzed Three Carbon Chain Extension Reactions with Acrolein Acetals. A Convenient Synthesis of Conjugated Dienals

Article abstract of DOI:10.1021/jo00319a004

A variety of vinylic halides has been found to react with acrolein or methacrolein acetals and amines with palladium catalysts to form 5-amino 3-enal acetals and/or dienal acetals.The reaction products yield 2,4-dienals on treatment with aqueous acids, in moderate to good yields.Crotonaldehyde dimethyl acetal also undergoes the reaction, but only in low yields. 3-Buten-2-one ethylene ketal reacted well under the same conditions, however, and Hofmann elimination and hydrolysis of the product amine gave (E,E)-3,5-heptadien-2-one in 90percent yield.