Alkyl Cyclopropyl Ketones in Catalytic Formal [3 + 2] Cycloadditions: The Role of SmI2 Catalyst Stabilization

Alkyl cyclopropyl ketones are introduced as versatile substrates for catalytic formal [3 + 2] cycloadditions with alkenes and alkynes and previously unexplored enyne partners, efficiently delivering complex, sp3-rich products. The key to effectively engaging this relatively unreactive new substrate class is the use of SmI2 as a catalyst in combination with substoichiometric amounts of Sm0; the latter likely acting to prevent catalyst deactivation by returning SmIII to the catalytic cycle. In the absence of Sm0, background degradation of the SmI2 catalyst can outrun product formation. For the most recalcitrant alkyl cyclopropyl ketones, catalysis is "switched-on" using these new robust conditions, and otherwise unattainable products are delivered. Combined experimental and computational studies have been used to identify and probe reactivity trends among alkyl cyclopropyl ketones, including more complex bicyclic alkyl cyclopropyl ketones, which react quickly with various partners to give complex products. In addition to establishing alkyl cyclopropyl ketones as a new substrate class in a burgeoning field of catalysis, our study provides vital mechanistic insight and robust, practical approaches for the nascent field of catalysis with SmI2.

Electrochemical Late-Stage Functionalization

Late-stage functionalization (LSF) constitutes a powerful strategy for the assembly or diversification of novel molecular entities with improved physicochemical or biological activities. LSF can thus greatly accelerate the development of medicinally relevant compounds, crop protecting agents, and functional materials. Electrochemical molecular synthesis has emerged as an environmentally friendly platform for the transformation of organic compounds. Over the past decade, electrochemical late-stage functionalization (eLSF) has gained major momentum, which is summarized herein up to February 2023.

Back to the future of organolanthanide chemistry

At the dawn of the development of structural organometallic chemistry, soon after the discovery of ferrocene, the description of the LnCp₃ complexes, featuring large and mostly trivalent lanthanide ions, was rather original and sparked curiosity. Yet, the interest in these new architectures rapidly dwindled due to the electrostatic nature of the bonding between π-aromatic ligands and 4f-elements. Almost 70 years later, it is interesting to focus on how the discipline has evolved in various directions with the reports of multiple catalytic reactivities, remarkable potential in small molecule activation, and the development of rich redox chemistry. Aside from chemical reactivity, a better understanding of their singular electronic nature - not precisely as simplistic as anticipated - has been crucial for developing tailored compounds with adapted magnetic anisotropy or high fluorescence properties that have witnessed significant popularity in recent years. Future developments shall greatly benefit from the detailed reactivity, structural and physical chemistry studies, particularly in photochemistry, electro- or photoelectrocatalysis of inert small molecules, and manipulating the spins' coherence in quantum technology.

Rh(III)-Catalyzed Enone Carbonyl/Ketone-Directed Aerobic C-H Olefination of Aromatics with Unactivated Olefins

A Rh(III)-catalyzed weak enone carbonyl/ketone-assisted aerobic oxidative C-H olefination of aromatics with unactivated alkenes has been developed. This protocol involves cross-dehydrogenative Heck-type olefination reaction of various substituted biologically relevant chalcones and aromatic ketones such as acetophenones and chromones with various functionalized unactivated olefins in moderate to good yields. Further, ortho-alkylation of chalcones with norbornene is also demonstrated. A possible reaction mechanism involving weak chelation-assisted C-H activation/insertion/β-hydride elimination was proposed and supported by the deuterium labeling studies.

Oxidative C-H/N-H Carbonylation of Benzamide by Nickel Catalysis with CO as the Carbonyl Source

An efficient and direct carbonylation of aminoquinoline benzamides has been developed using abundant and inexpensive Ni(OAc)₂·4H₂O as the catalyst and carbon monoxide as a cost-efficient C1 building block. This process features good functional-group tolerance and can be conducted on gram scale. The directing group can be easily removed under mild conditions.