Here we report palladium-catalyzed, regiodivergent [5 + 4] and [5 + 2] annulations of vinylethylene carbonates and allylidenemalononitriles affording over 50 medium-sized heterocycles in high isolated yields with excellent regioselectivities.

The 6,8-dioxabicyclo­[3.2.1]­octane (6,8-DOBCO) architecture widely exists in a broad spectrum of bioactive natural products, and the development of efficient and convenient protocols to construct this skeleton remains a challenging task. Here, we report a concise synthetic strategy for the single-step construction of 6,8-DOBCO frameworks from simple vinylethylene carbonates and amine-substituted enones. This protocol features a sequential reaction of N-allylic substitution, Diels–Alder cyclization, and intramolecular ketalization, which is promoted by metal-organo relay catalysis involving palladium/phosphoric acid or palladium/halogen-bonding catalytic system. Over 50 examples of 6,8-DOBCO derivatives with structural diversity have been facilely achieved with satisfactory synthetic results, including high levels of stereoselectivity, reasonable isolated yield, ample scope in reaction partners, high step economy, and operational simplicity.

Oxindoles and β-lactams are attractive structural motifs because of their unique biological importance. However, the fusion of the two moieties featuring 3,3′-spirocyclic scaffolds is a challenging task in organic synthesis. Herein we designed a novel type of oxindole-based azaoxyallyl cation synthons, which could readily participate in the [3 + 1] cyclization with sulfur ylides. With this protocol, a collection of 3,3-spiro­[β-lactam]-oxindoles were facilely produced in up to 94% yield with perfect diastereoselectivity.

An efficient on-water [2 + 1] annulation of diazo compounds and electron-deficient alkenes under catalyst-free conditions was developed, which allows the synthesis of cyclopropanes in a diastereodivergent manner.