All four stereoisomers of Δ(9)-tetrahydrocannabinol (Δ(9)-THC) were synthesized in concise fashion using stereodivergent dual catalysis. Thus, following identical synthetic sequences and applying identical reaction conditions to the same set of starting materials, selective access to the four stereoisomers of THC was achieved in five steps.

Chiral gold­(I) catalysts have been designed based on a modified JohnPhos ligand with a distal C 2-2,5-diarylpyrrolidine that creates a tight binding cavity. The C 2-chiral element is close to where the C–C bond formation takes place in cyclizations of 1,6-enynes. These chiral mononuclear catalysts have been applied for the enantioselective 5-exo-dig and 6-endo-dig cyclization of different 1,6-enynes as well as in the first enantioselective total synthesis of three members of the carexane family of natural products. Opposite enantioselectivities have been achieved in seemingly analogous reactions of 1,6-enynes, which result from different chiral folding of the substrates based on attractive aryl–aryl interactions.

Dialkyl biarylphosphine ligands, presented in the context of Pd-catalyzed cross-coupling reactions, have been extensively applied in gold(I) catalysis giving rise to numerous transformations and reaction pathways otherwise inaccessible under the action of other gold(I) catalysts. This review emphasizes how this privileged ligand class, as well as recent modifications on the biarylphosphine motive, have triggered the discovery of new reactivities in our research program. Finally, the introduction of chiral information on the ligand scaffold provides new solutions to challenging gold(I)-catalyzed enantioselective transformations. Scheme 2. Formal [4 + 2] cycloaddition of 1,6-arylenynes 1. Scheme 3. Access to hydroacenes via sequential Sonogashira coupling/gold(I)-catalyzed 1,7-enyne cyclization. Scheme 4. Bifunctional electrophilic reactivity of intermediate 10. Review Isr. J. Chem. 2020, 60, 360 -372 Scheme 5. Gold-catalyzed hydroarylation of alkynyl-indoles and synthetic application in total synthesis of Kopsia indole alkaloids. Scheme 6. Gold(I) catalyzed reactions of 1,6-enyne functionalized with propargyl acetate. Scheme 7. Enantioselective total synthesis of (+)-schisanwilsonene A. Scheme 8. Gold(I)-catalyzed [2 + 2 + 2] cycloaddition of 1,6-enynes. Scheme 12. Diverse reactivity of gold(I)-carbenes generated by retro-Buchner reaction.Scheme 13. Second generation 7-styryl-1,3,5-trimethyl-cycloheptatrienes. Isolated yield and cis/trans ratio of diastereosiomers in parentheses. In grey: yield and diastereoselectivity obtained with first gen. of cycloheptatriene.

Due to burgeoning interest in the pharmaceutical industry in exploiting optically active α-aminoboronic derivatives as bioisosteres of α-amino acid derivatives, the discovery of methods for their catalytic asymmetric synthesis is an important challenge. Herein, we establish that a chiral copper catalyst (generated in situ from commercially available components) can achieve the enantioselective synthesis of α-aminoboronic derivatives via the coupling of two readily available partners, a carbamate and a racemic α-chloroboronate ester. Furthermore, we describe mechanistic studies that played a key role in the development of this new method and that provide insight into the optimized process.