Advanced Synthesis & Catalysis 2010-12-01

Iridium Catalyzed Hydro-hydroxyalkylation of Butadiene: Carbonyl Crotylation.

JasonR Zbieg, Takeo Fukuzumi, MichaelJ Krische

Index: Adv. Synth. Catal. 352(14-15) , 2416-2420, (2010)

Full Text: HTML

Abstract

Exposure of alcohols 1a-1i to butadiene in the presence of a cyclometallated iridium catalyzed derived from allyl acetate, 4-methoxy-3-nitrobenzoic acid and BIPHEP (2,2'-bis(diphenylphosphino)biphenyl) results in hydrogen transfer to generate aldehyde-allyliridium pairs, which engage in C-C coupling to form products of carbonyl crotylation. Under related conditions using 1,4-butanediol as hydrogen donor, butadiene reductively couples to aldehydes 2e-2g and 2i to furnish carbonyl crotylation products 3e-3g and 3i. Thus, butadiene mediated carbonyl crotylation occurs with equal facility from the alcohol or aldehyde oxidation level with complete levels of branched regioselectivity.