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2025

Bloch, J. M.; Savelson, E.; Meng, A. Q.; Ericson, M. N.; Patel, I. U.; Dickie, D. A.; Tepe, J. J.; Harman, W. D. Tungsten-Enabled Diels–Alder Cycloaddition and Cycloreversion of Arenes and Alkynes: Divergent Synthesis of Highly Functionalized Barrelenes and Arenes. Journal of the American Chemistry 2025, 17, 30146-30153.
Publisher's Version
doi: 10.1021/jacs.5c08320

The Diels–Alder reaction of benzenes remains a significant synthetic challenge, owing to their highly stabilized aromatic cores. In this work, the dearomatization agent {WTp(NO)(PMe3)} is used to promote Diels–Alder reactions of dihapto-coordinated (η2) benzenes with alkynes. The resulting η2-barrelene complexes can be oxidized to liberate intact barrelenes. Alternatively, mild pyrolysis leads to the extraction of the corresponding tungsten-acetylene complex and concomitant formation of new arenes possessing substituents originating from the acetylene dienophiles.

Ou, X.; Kong, F.; Quirion, K. P.; Webber, C. K.; Dickie, D. A.; Ess, D. H.; Gunnoe, T. B. Synthesis of Quinoline-Based Rh–Sb Complexes: Inhibition of Halide Transfer to Access a Rh→Sb Z-Type Interaction. Organometallics 2025, 44, 1639-1643.
Publisher's Version
doi: 10.1021/acs.organomet.5c00187

We report the synthesis of Rh–Sb complexes using high valent Sb ligands, Q3SbCl2 (1, Q = 8-quinolinyl) and Q3SbF2 (2), from the low valent Rh precursor [(CO)2Rh(μ-Cl)]2 to afford the complexes [(κ4-Q3SbCl)Rh(CO)Cl][(CO)2RhCl2] (3) and (κ4-Q3SbF2)Rh(CO)Cl (4), respectively. The reaction of 1 with [(CO)2Rh(μ-Cl)]2 results in the transfer of chloride from Sb to Rh to give the ion pair 3 with a Rh–Sb bond for the cation that, according to computational analysis, has some covalent character. Replacing Sb–Cl with Sb–F bonds (i.e., compound 2) inhibited halide transfer and allowed formation of 4 with a Rh→Sb interaction that has more Z-type character than the Rh–Sb bond for complex 3. Molecular orbital and localized orbital bonding analyses are consistent with the proposed Rh→Sb interaction of 4 being more Z-type in character.

Simpson, S. R.; Jouad, K.; Clay, A. J.; Ghosh, A.; Wilde, J. H.; Dickie, D. A.; Vavere, A. L.; Neumann, K. D. Automated radiosynthesis of [18F]fluoromannitol on the Sofie Biosciences ELIXYS FLEX/CHEM system. Applied Radiation and Isotopes 2025, 225, 112076.
Publisher's Version
doi: 10.1016/j.apradiso.2025.112076
Bacterial infections remain a significant global health concern, exacerbated by rising antimicrobial resistance and a growing immunocompromised population. Improved diagnostic tools are essential to accurately detect infections, distinguish them from sterile inflammation, and reduce unnecessary antibiotic use that drives resistance. Positron Emission Tomography (PET) has emerged as a powerful non-invasive modality for detecting and monitoring infections in vivo, especially when conventional diagnostics are inconclusive.
[18F]Fluoromannitol is a novel PET radiopharmaceutical that selectively targets both Gram-positive and Gram-negative bacteria, enabling broad-spectrum imaging and differentiation from sterile inflammation. To support preclinical studies and facilitate broader research use, we report the automated synthesis of [18F]fluoromannitol using the ELIXYS FLEX/CHEM radiosynthesizer.
The synthesis was adapted from a manual protocol into a fully automated, two-pot, three-step process involving a nucleophilic fluorination, acid deprotection, and sodium borohydride reduction. Reaction conditions were optimized on the ELIXYS FLEX/CHEM platform. The fluorination was optimized for temperature and time to a yield of 78 ± 1.5%. Acid-catalyzed deprotection yielded an impurity when manual conditions were applied. A large increase in temperature was necessary in order to efficiently produced [18F]fluoromannose with >99% radiochemical purity, which was then reduced to [18F]fluoromannitol. The complete synthesis required approximately 136 minutes, yielding a 15 ± 0.9% activity yield, a 35 ± 2.0% radiochemical yield, >99% radiochemical purity, and a final pH of 5.5 ± 0.5.
This automated synthesis protocol supports reliable production of [18F]fluoromannitol and its broader adoption in bacterial infection imaging, with the potential to enhance early diagnosis and improve clinical management.