Abstract

The Annual Wolf Prize Symposia of the Israel Chemical Society (ICS) have become a significant component of the scientific landscape of the State of Israel. These highly attended events occur annually in late May or early June as part of the Wolf Prize week, usually one day before the award ceremony in the Knesset. This account covers the one-day symposium at the Weizmann Institute of Science on June 14, 2023, the Wolf Prize ceremony in the Knesset on June 15, and several other events in Israel that week, all honoring Chuan He, Jeffrey W. Kelly, and Hiroaki Suga.

The cover picture illustrates symbolically the critical step in π-acid catalysis as a bullfighting scene: a metal catalyst (the toreador) binds an alkyne and activates it for an attack by a nucleophile (the bull). Cover image by Dr. Igor Armiach.

Abstract

Density functional theory (DFT) is a powerful tool that can aid in the exploration and development of synthetic chemistry, and its use is often applied in the chemistry of gold(I) catalysis. In this review, we discuss two different facets of these calculations – namely, the exploration and explanation of anion effects, and the regioselectivity and speciation of gold(I)-catalysed reactions. The research described herein clearly shows the importance of including the anion in DFT studies of Au(I)-catalysed reactions, especially when using low polarity solvents, or where hydrogen-bonding is prevalent. Additionally, we show that whilst using DFT to study the selectivity of reactions can be successful, benchmarking the computational results against experimental data is vitally important for ensuring that the model is accurately describing the observed results.

Abstract

Gold catalysis has emerged as an efficient tool for the selective functionalisation of C−C multiple bonds. Despite significant progress in this field, the potential of asymmetric gold catalysis has not been fully explored to date. A historical retrospect on the progress in this area reveals that enantioselective gold catalysis is based on three pillars: Au(I) catalysis, Au(III) catalysis, and Au(I)/Au(III) redox catalysis. Irrespective of the mode of catalysis being operative, the design of new ligands is crucial for the development of gold-catalysed organic transformations. This minireview summarizes the progress made in the development of ligand design for enantioselective Au(I) catalysis, Au(III) catalysis, and Au(I)/Au(III) redox catalysis focusing on the ligands which were specially designed for gold catalysis.

Abstract

Thanks to their appealing properties, N-heterocyclic carbene (NHC) ligands gained considerable significance as highly powerful ancillary ligands in gold catalysis. While NHC-gold catalysis is still dominated by the classical imidazole-derived NHC ligands, annelated NHC systems, which feature fused aromatic rings to the carbenic heterocycle, have drawn wider attention over the last few years thanks to their unique structural and electronic properties. Fused polyaromatic NHCs are indeed versatile platforms that offer unique stereoelectronic tuning possibilities to exhibit superior activity and/or selectivity in NHC-gold catalysis. But their polycyclic scaffolds also provide further scope for functionalization and the introduction of chirality, stimuli-responsiveness, or cooperativity within the NHC-gold systems. In this review, the recent advances in this area are discussed and a particular attention is drawn on the unique role of the annelation.

Abstract

Over the last century, the fragrance industry had relied on the synthetic chemists for the development of new odors, but also for the replacement of some known materials due to allergy or toxicity. Transition metal-catalyzed transformations have allowed atom economy and synthetic efficiency for several transformations and they caught the attention of fragrance industrials. The metal-catalyzed cyclization reactions have been particularly successful toward the synthesis of key skeletons. This review highlights the developments of selected hedonic materials according to transition metal-catalyzed according to cycloisomerization reactions and related rearrangements.

Abstract

As part of our efforts to interface late transition metals with Lewis acidic main group fragments, we have decided to investigate gold complexes bearing halogermanes as Z-type ligands. Toward this end, we have synthesized complexes of general formula [(o-(Ph₂P)C₆H₄)₂(Ph)(X)GeAuCl] (X = F, Cl). Experimental and computational analyses indicate the presence of an Au→Ge interaction in both cases. Chloride abstraction reactions have also been investigated. In the case of X = Cl, double chloride abstraction with AgSbF₆ affords a putative dication that gradually abstracts fluoride from its counterion. This putative dication is also significantly more active as a catalyst than its monocationic analog in alkyne hydroamination reactions.

Abstract

A Au-catalyzed protocol for the enantioselective synthesis of molecular architectures containing an internal [5]helicene and two peripherical axial stereogenic elements is described. While the diasteroselectivity of the double alkyne hydroarylation sequence is not optimal, and mixtures that contain similar amounts of two of the four possible diasteromeric products are obtained (one C₂ and one non-symmetric), the assembly of the C₂-symmetric isomer often occurs with high enantioselectivity (up to 98 % ee). The absolute configurations of the products obtained were determined by X-ray crystallography. Studies on the thermal racemization of the internal [5]helicene moiety in the C₂-symmetric isomers determined the half-life of this element to be approximately 3 h at 50 °C.