An efficient tertiary alkylation reaction of olefins with 1,3-dicarbonyl compounds was developed by virtue of copper catalyst without the use of expensive ligands or additives. In contrast to alkyl Heck-type reaction, alkyl halide is not required. Notably, by varying the nitrogen and air atmosphere, the reaction selectively produces alkylation and alkylation−oxygenation products, respectively. Initial investigations revealed that an α-carbonyl alkyl radical species might be involved in the process.
Direct oxidative C(sp)−H/C(sp3)−H cross‐coupling offers an ideal and environmentally benign protocol for C(sp)−C(sp3) bond formations. As such, reactivity and site‐selectivity with respect to C(sp3)−H bond cleavage have remained a persistent challenge. Herein is reported a simple method for iron‐catalyzed/silver‐mediated tertiary alkylation of terminal alkynes with readily available and versatile 1,3‐dicarbonyl compounds. The reaction is suitable for an array of substrates and proceeds in a highly selective manner even employing alkanes containing other tertiary, benzylic, and C(sp3)−H bonds alpha to heteroatoms. Elaboration of the products enables the synthesis of a series of versatile building blocks. Control experiments implicate the in situ generation of a tertiary carbon‐centered radical species.
A radical-mediated oxidative cross-coupling of readily accessible α-alkylated styrenes with 1,3-dicarbonyl compounds utilizing a combination of Cu(OAc) and air as a catalytic system is described. Rather than requiring α-halocarbonyl compounds, this efficient approach enables direct installation of tertiary functionalized alkyl motifs to olefins with simple carbonyl derivatives. The novel protocol is characterized with high allylic selectivities via a competing β-H elimination. Both radical-clock and -trapping experiments provided clear-cut evidence for the intermediacy of an α-keto carbon-centered radical.
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