Catalytic Carbonyl Allylation Using Terminal Alkenes as Nucleophiles

Abstract

We herein describe a cobalt/Xantphos system enabling highly challenging catalytic nucleophilic functionalizations of low-reactive carbonyl compounds via C(sp³)-H bond cleavage. The combination of Co(acac)₂, Xantphos, and AlMe₃ was crucial to convert terminal alkenes into nucleophilic allylation reagents. With the aid of this system, CO₂ and various ketones were efficiently allylated using various allylarenes, 1,4-dienes, and simple α-olefins. The regioselectivity switched depending on the alkenes and ketones used. Furthermore, the intramolecular cyclization of ketoalkenes provided tertiary homoallylic cycloalkanols with good diastereoselectivity, leading to demonstration of a short-step synthesis of biologically active compound, tramadol.