Terpenes constitute one of the most structurally varied classes of natural products. A wide range of these structures are produced in nature by type I terpene cyclase enzymes, but such reactivity has proven difficult to reproduce in solution with man-made systems. Herein we report the shortest synthesis of the tricyclic sesquiterpene presilphiperfolan-1β-ol to date, utilizing the supramolecular resorcinarene capsule as catalyst for the key step. This synthetic approach also allows access to unnatural derivatives of the natural product, which would not be accessible through the biosynthetic machinery. Additionally, this study provides useful insight into the biosynthesis of the presilphiperfolanol natural products, including the first direct experimental evidence for the proposed biosynthetic connection between caryophyllene and the presilphiperfolanols.

This review comprises two major parts, which have chiral metal enolates as their focus. In the first part, we discuss transition-metal-catalyzed conjugate additions leading to chiral enolates, which are then subsequently functionalized by reactions with electrophiles, both further catalyzed or uncatalyzed. The second part deals with base-generated enolates and their use in asymmetric transition-metal-catalyzed processes.

Self-assembled molecular capsules, host structures that form spontaneously when their building blocks are mixed, have been known since the 1990s. They share some basic similarities with enzyme pockets, as they feature defined hydrophobic binding pockets that are able to bind molecules of appropriate size and shape. The potential to utilize such host structures for catalysis has been explored since their discovery; however, applications that solve current challenges in synthetic organic chemistry have remained limited. In this short article, we discuss the challenges associated with the use of molecular capsules as catalysts, and highlight some recent applications of supramolecular capsules to overcome challenges in synthetic organic chemistry.

Stereoselective copper-catalyzed conjugate additions of organometallic reagents serve as a versatile tool in the total syntheses of diverse natural compounds and pharmaceutical agents.

Herein, we describe the fast, chemoselective, and clean reduction of imines with zirconocene chloride hydride. The reaction works well on aromatic and enolizable aliphatic aldimines, as well as ketimines. A range of N-protecting groups and various functional groups were tolerated in the imine struc-

Building complex structures from simple starting materials is important for effective organic synthesis. In this context, domino reactions comprising hydrozirconation of alkenes, their subsequent utilization in a copper-catalyzed conjugate addition to enones, followed by electrophilic trapping of the formed zirconium enolates with activated alkene and carbocations are described. Reactivity of metal enolates was studied by DFT calculations.

No abstract

The search for mild, user-friendly, easily accessible, and robust organometallic reagents is an important feature of organometallic chemistry. Ideally, new methodologies employing organometallics should be developed with respect to practical applications in syntheses of target compounds. In this short review, we investigate if organozirconium reagents can fulfill these criteria. Organozirconium compounds are typically generated via in situ hydrozirconation of alkenes or alkynes with the Schwartz reagent. Alkyl and alkenylzirconium reagents have proven to be convenient in conjugate additions, allylic substitutions, cross-coupling reactions, and additions to carbonyls or imines. Furthermore, the Schwartz reagent itself is a useful reducing agent for polar functional groups.1 Introduction2 Synthesis and Generation of the Schwartz Reagent3 Structure and Properties of Cp2Zr(H)Cl4 Reactivity of Organozirconium Reagents4.1 Asymmetric Conjugate Addition4.2 Asymmetric Allylic Alkylations4.3 Desymmetrization Reactions4.4 Cross-Coupling Reactions4.5 1,2-Additions5 Conclusions