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1. Enantioselective Synthesis of (−)‐Halenaquinone

   https://doi.org/10.1002/anie.201805370  

   Goswami, Subir; Harada, Kenichi; El‐Mansy, Mohamed F.; Lingampally, Rajinikanth; Carter, Rich G. (June 2018, Angewandte Chemie International Edition)

   Abstract The efficient, 12–14 step (LLS) total synthesis of (−)‐halenaquinone has been achieved. Key steps in the synthetic sequence include: (a) proline sulfonamide‐catalyzed, Yamada–Otani reaction to establish the C6 all‐carbon quaternary stereocenter, (b) multiple, novel palladium‐mediated oxidative cyclizations to introduce the furan moiety, and (c) oxidative Bergman cyclization to form the final quinone ring. 

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2. Diastereoselective Synthesis of Benzoxanthenones

   https://doi.org/10.1002/asia.201901727  

   Neuhaus, William_C; Kozlowski, Marisa_C (March 2020, Chemistry – An Asian Journal)

   Abstract An oxidative catalytic vanadium(V) system was developed to access the naturally nonabundant diastereomers of carpanone from the corresponding alkenyl phenol monomer in one pot by tandem oxidation, oxidative coupling, and 4+2 cyclization. This system was applied to the synthesis of two other analogues of carpanone. Mild oxidizing silver salts were used as the terminal oxidant to minimize background oxidation which produces the natural diastereomer of carpanone. Further, the first examples of enantioselective oxidative benzoxanthenone formation are reported. Solvent polarity has a strong effect on enantioselectivity, consistent with a mechanism involving binding of vanadium Schiff base catalysts to the alcoholic moiety of the alkenyl phenols during the cyclization step. 

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3. Bioinspired Total Synthesis of Pyritide A2 through Pyridine Ring Synthesis

   https://doi.org/10.1002/anie.202212299  

   Hooper, Annie R.; Oštrek, Andraž; Milian‐Lopez, Ana; Sarlah, David (October 2022, Angewandte Chemie International Edition)

   Abstract Pyritides belong to the ribosomally synthesized and post‐translationally modified peptide class of natural products that were recently genome‐predicted and are structurally defined by unique pyridine‐containing macrocycles. Inspired by their biosynthesis, proceeding through peptide modification and cycloaddition to form the heterocyclic core, we report the chemical synthesis of pyritide A2 involving pyridine ring synthesis from an amino acid precursor through aza‐Diels–Alder reaction. This strategy permitted the preparation of the decorated pyridine core with an appended amino acid residue in two steps from a commercially available arginine derivative and secured pyritide A2 in ten steps. Moreover, the synthetic logic enables efficient preparation of different pyridine subunits associated with pyritides, allowing rapid and convergent access to this new class of natural products and analogues thereof. 

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4. Enantioselective Synthesis of (−)‐10‐Hydroxyacutuminine

   https://doi.org/10.1002/anie.202117480  

   Grünenfelder, Denise C.; Navarro, Raul; Wang, Haoxuan; Fastuca, Nicholas J.; Butler, John R.; Reisman, Sarah E. (February 2022, Angewandte Chemie International Edition)

   Abstract An enantioselective synthesis of (−)‐10‐hydroxyacutuminine is reported. Central to our strategy is a photochemical [2+2] cycloaddition that forges two of the quaternary stereocenters present in the acutumine alkaloids. A subsequent retro‐aldol/Dieckmann sequence furnishes the spirocyclic cyclopentenone. Efforts to chlorinate the acutumine scaffold at C10 under heterolytic or radical deoxychlorination conditions led to the synthesis of an unexpected cyclopropane‐containing pentacycle. 

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5. Modular Synthesis of a Versatile Double‐Allylation Reagent for Complex Diol Synthesis

   https://doi.org/10.1002/anie.202103435  

   Dorn, Stanna K.; Tharp, Annika E.; Brown, M. Kevin (June 2021, Angewandte Chemie International Edition)

   Abstract Double‐allylation reagents allow for the construction of highly complex molecules in an expedient fashion. We have developed an efficient, modular, and enantioselective approach towards accessing novel variants of these reagents through Cu/Pd‐catalyzed alkenylboration of alkenylboron derivatives. Importantly, we demonstrate novel use of an allylBdan reagent directly in a stereocontrolled allylation without initial deprotection to the boronic ester. These allylation products are employed in a second intermolecular allylation to access complex diol motifs, which has yet to be shown with these types of double‐allylation reagents. Overall, the modularity of this approach and the ease in which complex structural motifs can be accessed in a rapid manner signify the importance and utility of this method. 

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