- Iridium Catalyzed Hydro-hydroxyalkylation of Butadiene: Carbonyl Crotylation.
Iridium Catalyzed Hydro-hydroxyalkylation of Butadiene: Carbonyl Crotylation.
Advanced synthesis & catalysis (2010-12-18)
Jason R Zbieg, Takeo Fukuzumi, Michael J Krische
PMID21165157
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.
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