Syntheses of Conjugated Dienes from 1-Alkenylboronic Acids by Palladium (II) Salt

Syntheses of Conjugated Dienes from 1-Alkenylboronic Acids by Palladium (II) Salt

The reactions of (E)-1-hexenylboronic acid (1) or (E)-${\beta}$-phenylethenylboronic acid (2) with various olefins in acetonitrile at room temperature in the presence of lithium palladium chloride and triethylamine gave the corresponding (E, E)-conjugated dienes stereospecifically in good yields. (E)-${\beta}$-Phenylethenylboronic acid (2) was more reactive than (E)-1-hexenylboronic acid (1) in these vinylations. And these vinylations were also carried out catalytically when 10 mol % of lithium palladium chloride and cupric chloride, as the reoxidant of palladium, or 10 mol % of palladium acetate and mercuric acetate were added instead of stoichiometric amount of lithium palladium chloride.