Nickel-catalyzed intramolecular homoallylation of ω-dienyl aldehyde

[GRAPHICS] In the presence of a catalytic amount of Ni(acac)(2), E3B and Et2Zn nicely promote a reductive homoallylic cyclization of omega -dienyl aldehydes and provide 2-allylcyclopentanols and -cyclohexanols with high stereoselectivity in excellent yield, The reaction requires only two kinds of commercially available, inexpensive reagents, Ni(acac)(2) and Et2Zn or Et3B, and completes at room temperature within 30 min with Et2Zn and 1-2 days with Et3B. No ligand additives (e.g., phosphine, nitrogen compounds) are required.