Boronate ester bullvalenes are now accessible in two to four operationally simple steps. This unlocks late-stage diversification through Suzuki cross-coupling reactions to give mono-, di-, and trisubstituted bullvalenes. Moreover, a linchpin strategy enables preprogrammed installation of two different substituents. Analysis of solution phase isomer distributions and singlecrystal X-ray structures reveals that isomer preference in the crystal lattice is due to general shape selectivity.

A fluxional bis‐monodentate ligand, based on the archetypal shape‐shifting molecule bullvalene, self‐assembles with M2+ (M=Pd2+ or Pt2+) to produce a highly complex ensemble of permanently fluxional coordination cages. Metal‐mediated self‐assembly selects for an M2L4 architecture while maintaining shape‐shifting ligand complexity. A second level of simplification is achieved with guest‐exchange; the binding of halides within the M2L4 cage mixture results in a convergence to a cage species with all four ligands present as the “B isomer”. Within this confine, the reaction graph of the bullvalene is greatly restricted, but gives rise to a mixture of 38 possible diastereoisomers in rapid exchange. X‐ray crystallography reveals a preference for an achiral form consisting of both ligand enantiomers. Through a combination of NMR spectroscopy and DFT calculations, we elucidate the restricted isomerisation pathway of the permanently fluxional M2L4 assembly.

There is growing interest in the biobased production of lipids from algae. These lipids have a range of uses including nutritional supplements and precursors to biodiesel. Single-cell thraustochytrids are especially attractive in this regard in that they can produce over 50% of their weight as triglycerides. Furthermore, the distribution of saturated and unsaturated triglycerides can be modulated by changes in strain variation and fermentation conditions. Nonetheless, there remains a need for versatile downstream processing to enrich these so-called "single cell oils" into classes based on degree of unsaturation. In this study, we report a novel strategy for enriching saturated triglycerides produced in thraustochytrids. The method features direct reaction of elemental sulfur with the algae oil extract. Sulfur copolymerizes with >90% of the unsaturated triglycerides, providing a new route to a class of materials previously used in environmental remediation, Li−S battery cathodes, slow-release fertilizers, and insulation. The unreacted oil is enriched in saturated triglycerides, which can be isolated by extraction for potential use in biodiesel production. In this way, a single batch of sustainably produced algae oil can be converted into multiple useful products in a single step.

The stereomutation of substituted bullvalenes is an inevitable consequence of the valence isomerism that automerizes this unique fluxional hydrocarbon. The introduction of external stereogenicity in the substituents expands the reaction graphs and leads to a wealth of complex diastereochemical relationships. In this communication, we explore these possibilities and prepare a range of stereochemically rich substituted bullvalenes. This includes a series of disubstituted bullvalenes with two external stereocenters as a platform for fluxional, shape-diverse compound libraries. We also prepare a tethered bisbullvalene with central stereogenicity in the tether as an ensemble of 900 unique isomers that are completely stereomutable.

The fluxional structure of bullvalene is expanded by the discovery of a [5,5]-sigmatropic rearrangement of dialkenyl substituted derivatives. This gives rise to tetrahydro-1,8-ethenoheptalenes (THEH), representing the first examples of this tricyclic scaffold. Variation of the substitution pattern alters the product distribution, including one thermodynamically balanced between THEH and bullvalene isomers. DFT calculations are used to explore the thermodynamic landscape and reaction mechanism revealing a pretransition state bifurcation leading to a concerted ambimodal rearrangement pathway.