Exploring Cuneanes as Benzene Isosteres and Energetic Materials: Scope and Mechanistic Investigations into Regioselective Rear-rangements from Cubanes

Abstract

Cuneane is a strained hydrocarbon accessible via metal-catalyzed isomerization of cubane. The carbon atoms of cuneane define a polyhedron of the C2v point group with six faces- two triangular, two quadrilateral, and two pentagonal. The rigidity, strain, and unique exit vectors of the cuneane skeleton make it a potential scaffold of interest for the synthesis of functional small molecules and materials. However, the limited previous synthetic efforts towards cuneanes have focused on mono-substituted or redundantly substituted systems such as permethylated, perfluorinated, and bis(hydroxymethylated) cu-neanes. Such compounds, particularly rotationally symmetric redundantly substituted cuneanes, have limited potential as building blocks for the synthesis of complex molecules. Reliable, predictable, and selective syntheses of poly-substituted cuneanes bearing more complex substitution patterns would facilitate the study of this ring system in myriad applications. Herein, we report the regioselective, AgI-catalyzed isomerization of asymmetrically 1,4-disubstituted cubanes to cuneanes. In-depth DFT calculations provide a charge-controlled regioselectivity model and direct dynamics simulations indicate that the non-classical carbocation is short-lived and dynamic effects augment the charge model.

Stellane at the Forefront: Derivatization and Reactivity Studies of a Promising Saturated Bioisostere of ortho‐Substituted Benzenes

“…As we tunnel deeper into the results, this discussion endeavors to shed light on the potential of new 1,5-disubstituted stellane core 45 in bridging this evident gap and its consequential impact on future research trajectories. The 1-(methoxycarbonyl)stellane-5carboxylic acid 4, synthesized in our prior work 45 , aligns conceptually with the extensively investigated 1-(methoxycarbonyl)cubane-4-carboxylic acid 39,46,49,[51][52] . This positions it as a central precursor for the synthesis of a potentially broad spectrum of disubstituted stellanes and also offers pathways for exploring mono-functional variants.…”

Computational Research on Ag(I)-Catalyzed Cubane Rearrangement: Mechanism, Metal and Counteranion Effect, Ligand Engineering, and Post-Transition-State Desymmetrization

“…When a 1,6disubstituted cubane is used as the substrate, two products, Prod1 and Prod2, can be generated depending on the metal, ligand, and counteranion employed. In 2023, Lam, 34 Nagasawa, 35 and Stephenson 36 reported new progress on this reaction nearly at the same time. In Lam's report, a mild strategy using AgNTf 2 as the catalyst selectively yielded Prod1 at room temperature with dichloromethane (DCM) as the solvent (Figure 1).…”

“…Notably, very recently, Paton and Stephenson performed calculations on a similar system using CF 3 the regioselectivity is controlled by the charge. 36 In this study, we investigate the mechanism using density functional theory (DFT), high-level coupled cluster (DLPNO−CCSD(T)), and quasi-classical molecular dynamics calculations and, more importantly, attempt to propose improved catalytic systems based on a mechanistic understanding. This research aims to address the following questions: (1) Is the proposed mechanism energetically reasonable and which step determines the ■ RESULTS AND DISCUSSION Mechanism.…”