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1. Total Syntheses of (±)‐Dracocephalone A and (±)‐Dracocequinones A and B

   https://doi.org/10.1002/anie.202210821  

   Hwang, Taehwan ; Tuccinardi, Joseph P. ; Beard, Alexandra A. ; Jackson, Amy C. ; Jung, Min J. ; Wood, John L. ( October 2022 , Angewandte Chemie International Edition)

   Described herein are the first total syntheses of (±)‐dracocephalone A (1) and (±)‐dracocequinones A (4) and B (5). The synthesis was initially envisioned as proceeding through an intramolecular isobenzofuran Diels–Alder reaction, a strategy that eventually evolved into a Lewis acid‐promoted spirocyclization. This highly diastereoselective transformation set the stage fortrans‐decalin formation and a late‐stage Suárez oxidation that produced a [3.2.1] oxabicycle suited for conversion to1. Brønsted acid‐mediated aromatization, followed by a series of carefully choreographed oxidations, allowed for rearrangement to a [2.2.2] oxabicycle poised for conversion to4and5.

    

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2. Syntheses of Molybdenum and Tungsten Imido Alkylidene Complexes that Contain a Bidentate Oxo/Thiolato Ligand

   https://doi.org/10.1002/hlca.202000068  

   Tafazolian, Hosein ; VenkatRamani, Sudarsan ; Tsay, Charlene ; Schrock, Richard R. ; Müller, Peter ( May 2020 , Helvetica Chimica Acta)

   3,3′,5,5′‐Tetra‐tert‐butyl‐2′‐sulfanyl[1,1′‐biphenyl]‐2‐ol (H₂[^tBu₄OS]) was prepared in 24 % yield overall from the analogous biphenol using standard techniques. Addition of H₂[^tBu₄OS] to Mo(NAr)(CHCMe₂Ph)(2,5‐dimethylpyrrolide)₂led to formation of Mo(NAr)(CHCMe₂Ph)[^tBu₄OS], which was trapped with PMe₃to give Mo(NAr)(CHCMe₂Ph)[^tBu₄OS](PMe₃) (1(PMe₃)). An X‐ray crystallographic study of1(PMe₃) revealed that two structurally distinct square pyramidal molecules are present in which the alkylidene ligand occupies the apical position in each. Both1(PMe₃)_Aand1(PMe₃)_Bare disordered. Mo(NAd)(CHCMe₂Ph)(^tBu₄OS)(PMe₃) (2(PMe₃); Ad=1‐adamantyl) and W(NAr)(CHCMe₂Ph)(^tBu₄OS)(PMe₃) (3(PMe₃)) were prepared using analogous approaches.1(PMe₃) reacts with ethylene (1 atm) in benzene within 45 minutes to give an ethylene complex Mo(NAr)(^tBu₄OS)(C₂H₄) (4) that is isolable and relatively stable toward loss of ethylene below 60 °C. An X‐ray study shows that the bond distances and angles for the ethylene ligand in4are like those found for bisalkoxide ethylene complexes of the same general type. Complex1(PMe₃) in the presence of one equivalent of B(C₆F₅)₃catalyzes the homocoupling of 1‐decene, allyltrimethylsilane, and allylboronic acid pinacol ester at ambient temperature.1(PMe₃),2(PMe₃), and3(PMe₃) all catalyze the ROMP ofrac‐endo,exo‐5,6‐dicarbomethoxynorbornene (rac‐DCMNBE) in the presence of B(C₆F₅)₃, but the polyDCMNBE that is formed has a random structure.

    

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3. Dissipative Formation of Covalent Basket Cages

   https://doi.org/10.1002/anie.202207418  

   Liyana Gunawardana, Vageesha W. ; Finnegan, Tyler J. ; Ward, Carson E. ; Moore, Curtis E. ; Badjić, Jovica D. ( July 2022 , Angewandte Chemie International Edition)

   Living systems use chemical fuels to transiently assemble functional structures. As a step toward constructing abiotic mimics of such structures, we herein describe dissipative formation of covalent basket cage CBC5by reversible imine condensation of cup‐shaped aldehyde2(i.e., basket) with trivalent aromatic amine4. This nanosized [4+4] cage (V=5 nm³,M_w=6150 Da) has shape of a truncated tetrahedron with four baskets at its vertices and four aromatic amines forming the faces. Importantly,tris‐aldehyde basket2and aliphatictris‐amine7undergo condensation to give small [1+1] cage6. The imine metathesis of6and aromatictris‐amine4into CBC5was optimized to bias the equilibrium favouring6. Addition of tribromoacetic acid (TBA) as a chemical fuel perturbs this equilibrium to result in the transient formation of CBC5, with subsequent consumption of TBA via decarboxylation driving the system back to the starting state.

    

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4. Dissipative Formation of Covalent Basket Cages

   https://doi.org/10.1002/ange.202207418  

   Liyana Gunawardana, Vageesha W. ; Finnegan, Tyler J. ; Ward, Carson E. ; Moore, Curtis E. ; Badjić, Jovica D. ( July 2022 , Angewandte Chemie)

   Living systems use chemical fuels to transiently assemble functional structures. As a step toward constructing abiotic mimics of such structures, we herein describe dissipative formation of covalent basket cage CBC5by reversible imine condensation of cup‐shaped aldehyde2(i.e., basket) with trivalent aromatic amine4. This nanosized [4+4] cage (V=5 nm³,M_w=6150 Da) has shape of a truncated tetrahedron with four baskets at its vertices and four aromatic amines forming the faces. Importantly,tris‐aldehyde basket2and aliphatictris‐amine7undergo condensation to give small [1+1] cage6. The imine metathesis of6and aromatictris‐amine4into CBC5was optimized to bias the equilibrium favouring6. Addition of tribromoacetic acid (TBA) as a chemical fuel perturbs this equilibrium to result in the transient formation of CBC5, with subsequent consumption of TBA via decarboxylation driving the system back to the starting state.

    

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5. Phosphonium‐based polyelectrolyte networks with high thermal stability, high alkaline stability, and high surface areas

   https://doi.org/10.1002/pola.29298  

   Yang, Xiaoyan ; Smith, Rhett C. ( December 2018 , Journal of Polymer Science Part A: Polymer Chemistry)

   Phosphonium‐containing polyelectrolyte networks (PENs) (P1–P4) were prepared by cyclotrimerization of bis(4‐acetylphenyl)diphenylphosphonium bromide (M1) and 1,4‐diacetylbenzene (M2) withp‐toluene sulfonic acid in variousM1:M2ratios (1,0, 1:1, 1:2, and 1:4). The relative abundance of the PAr₄⁺units in each PEN was demonstrated to influence thermal stability, alkaline stability, water uptake, surface area, and CO₂uptake in predictable ways. Impressively, PENs with NTf₂⁻counterions (Tf = CF₃SO₃) did not exhibit 5% mass loss until heating above 400 °C. Alkaline stability, tested by challenging a PEN with 6MNaOH(aq) at 65 °C for 120 h, increased with increasing PAr₄⁺content, which reflected the enhanced reactivity of the HO⁻anion in more hydrophobic materials (i.e., PENs with lowerM1:M2ratios). The specific surface areas estimated by Brunauer‐Emmett‐Teller (BET) analysis for these PENs were above 60 m²/g under N₂and nearly 90 m²/g under CO₂. Notably,P3(in which 33% of monomers comprise a phosphonium moiety) exhibited a CO₂uptake affinity of one CO₂molecule adsorbed for every phosphonium site. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019,57, 598–604

    

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