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Two approaches to the synthesis of an oxabicyclic pyrrolidine‐6‐one are described using enzymatic resolution and gold‐mediated catalysis as key steps toward enantiopure compounds previously reported as racemic mixtures. Addition of Grignard reagents to the ketone afforded a variety of diversified tertiary alcohols of interest for their reported pharmacological activities. [ABSTRACT FROM AUTHOR]

Identification of a common Diels–Alder pattern in three classes of bioactive natural products led us to study the synthesis and cycloaddition of a new class of cyclic dienes readily available from β,γ‐unsaturated lactams. A practical and readily scalable route to the parent p‐methoxybenzyl‐protected 6‐ and 7‐membered β,γ‐unsaturated lactams was developed. These were readily transformed into the corresponding O‐silylated dienes, which were reacted with dimethyl and diethyl fumarate to yield stereoselectively highly functionalized bicyclic adducts. These exhibited unexpected and versatile transformations upon acid hydrolysis depending on the nature of the dienophile substituents and the acid catalyst. All reactions have been performed on multigram quantities. These transformations provide a convenient, economical, and easily scalable pathway for the rapid construction of functionally and stereochemically dense privileged scaffolds for the construction of libraries of natural products‐inspired molecules of pharmacological relevance. [ABSTRACT FROM AUTHOR]

Efficient four- and five-step routes to access functionalized bicyclo[3.2.1]oct-2-ene and bicyclo[3.3.1]nonadiene via indium-mediated cycloisomerization of 1,6-enynes has been developed. This atom-economical catalytic process was optimized and relied on the efficiency of InCl3 leading to the preparation of functionalized bicyclic adducts in up to 99% isolated yield. The cyclization occurred on two different processes (5-exo versus 6-endo pathway) and were influenced by the substitution of the alkynyl moiety. The exo process was favored for non-substituted alkynes whereas the endo pathway was generally observed for substituted alkynes. Then, the presence of electron-withdrawing groups on the aryl substituted alkyne increased the ratio of the exo isomer. DFT calculations were performed on stability of intermediates and corroborated the intervention of InCl3. [ABSTRACT FROM AUTHOR]

Herein, we report a convenient synthesis of unprecedented aza-diketopiperazines (aza-DKPs). The strategy is based on selective diversification of bicyclic aza-DKP scaffolds by click reaction, N-acylation, and/or N-alkylation. These scaffolds containing either azido or amino groups were obtained by a key Rh(I)-catalyzed hydroformylative cyclohydrocarbonylation reaction of allyl-substituted aza-DKP. The methodology is readily amenable to the parallel synthesis of original aza-DKPs to enlarge the chemical diversity of aza-heterocycles., Competing Interests: The authors declare no competing financial interest.