Abstract: Cobalt(I) catalysts equipped with bisphosphine ligands can be used to promote formal (3 + 2 + 2) intramolecular cycloadditions of enynylidenecyclopropanes of type 1. The method provides synthetically appealing 5,7,5-fused tricyclic systems in good yields and with complete diastereo- and chemoselectivity. Interestingly, its scope differs from that of previously reported annulations based on precious metal catalysts, specifically rhodium and palladium. Noticeably, density functional theory calculations confirm that the mechanism of the reaction is also different from those proposed for these other catalysts.

External link: https://pubs.acs.org/doi/10.1021/acs.orglett.3c03511

Abstract: Low-valent cobalt complexes equipped with phosphorous type of ligands can promote the intramolecular (3+2) cycloaddition of alkylidenecyclopropanes (ACPs) with alkenes and with allenes. Dienes can also be used as partners, but they afford seven-membered cycloadducts. The reactions are fully diastereoselective and, in some cases, we also observed moderate enantioselectivities, especially when using chiral phosphite ligands

External link: https://onlinelibrary.wiley.com/doi/10.1002/adsc.202301040

Abstract: This article describes the discovery and development of a palladium-catalyzed asymmetric C–H olefination of 2-hydroxybiaryls. The strategy allows a direct assembly of optically active, axially chiral 2-substituted-2′-hydroxybiaryls from readily available precursors and demonstrates that the native hydroxy unit of the substrates can work as an efficient directing group for the C–H activation. This represents a substantial advantage over other approaches that require the preinstallation of metal coordinating units. The simplicity of the approach and versatility of the products allow a practical and efficient synthesis of a broad variety of optically active binaphthyl derivatives

External link: https://pubs.acs.org/doi/10.1021/acscatal.3c03867