A Ru(II)-catalyzed peri-C–H activation of α-naphthols with strained alkylidene β-lactones and β-lactams is reported. With alkylidene β-lactones, the reaction proceeds via controlled strain release, favoring an allylic substitution pathway to afford a broad range of seven-membered oxepines in high yields. In contrast, the corresponding β-lactams suppress this reactivity and undergo Heck-type functionalization, leading to functionalized β-lactams. The protocol is operationally simple and scalable, displays a broad substrate scope, and can be extended to distal functionalization of indoles. The synthetic utility of this method is highlighted through downstream product diversification, which further enhances the scaffold diversity.
Mondal et al. (Mon,) studied this question.