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In the preparation of organolithium reagents, the use of highly activated lithium metal surfaces is essential. Currently, commercially available sources provide high surface area lithium in the form of powders or dispersions. Our group has presented a new approach to synthesize lithium with clean and high surface areas up to 100 times greater than conventional Li-dispersion. Our method involves the use of liquid ammonia (NH3) to effectively clean the lithium surface, resulting in the controlled dendritic growth of lithium structures along the flask wall. This freshly synthesized and highly activated lithium exhibits consistency and reliability, enabling the scalable production of organolithium reagents, ranging from 0.1 mmol to 0.5 mole. Herein, we outline the procedure for applying 5 grams of Li-dendrites in the synthesis of (trimethylsilyl)methylchloride, highlighting the potential impact of our method on organometallic chemistry.
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Enantioselective Organocatalytic Conjugate Addition in a Tandem Synthesis of δ-Substituted Cyclohexenones and Four-Step Total Synthesis of Penienone
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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.more » « less
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Telechelic polymers, polymers with two reactive end-groups, are sought after for their role in synthesizing macromolecules with complex structures such as multiblock copolymers and graft polymers. Many strategies for the synthesis of telechelic polymers from vinyl monomers using controlled radical polymerizations and anionic polymerizations exist. However, polyolefins—which account for the major fraction of polymer production—are not easily synthesized with two reactive end-groups. This difficulty is related to the sensitivity of olefin polymerization catalysts and their propensity for intramolecular chain transfer reactions. As a result, the most common strategies to access telechelic polyethylene and polypropylene (the two major polyolefins) do not rely on the insertion polymerization of ethylene nor propylene but rather on the polymerization of dienes or cyclic olefins. Nonetheless, recent advances in insertion polymerization and post-polymerization functionalization have resulted in the emergence of novel synthetic methods to access telechelic polyolefins. We here present a comprehensive review of all of these strategies to synthesize telechelic polyolefins.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.orglett.2c01976
