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A Polyketide Cyclase That Forms Medium-Ring Lactones. | LitMetric

A Polyketide Cyclase That Forms Medium-Ring Lactones.

J Am Chem Soc

State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai, China.

Published: January 2021

Medium-ring lactones are synthetically challenging due to unfavorable energetics involved in cyclization. We have discovered a thioesterase enzyme DcsB, from the decarestrictine C1 () biosynthetic pathway, that efficiently performs medium-ring lactonizations. DcsB shows broad substrate promiscuity toward linear substrates that vary in lengths and substituents, and is a potential biocatalyst for lactonization. X-ray crystal structure and computational analyses provide insights into the molecular basis of catalysis.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8126169PMC
http://dx.doi.org/10.1021/jacs.0c11226DOI Listing

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Article Synopsis
  • Inherently chiral medium-ring derivatives, crucial for fields like materials science and asymmetric catalysis, face challenges in enantioselective assembly, particularly using organocatalysis.
  • Researchers introduce a novel method using N-heterocyclic carbenes (NHC) for a high-order (5 + 3) annulation of specific indolyl compounds with ynals, leading to the efficient creation of diverse eight-membered lactones.
  • The study highlights the successful scaling up of production and potential applications of these lactones, demonstrating their practical relevance in synthetic chemistry.
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A Polyketide Cyclase That Forms Medium-Ring Lactones.

J Am Chem Soc

January 2021

State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai, China.

Medium-ring lactones are synthetically challenging due to unfavorable energetics involved in cyclization. We have discovered a thioesterase enzyme DcsB, from the decarestrictine C1 () biosynthetic pathway, that efficiently performs medium-ring lactonizations. DcsB shows broad substrate promiscuity toward linear substrates that vary in lengths and substituents, and is a potential biocatalyst for lactonization.

View Article and Find Full Text PDF

A strategy for the synthesis of medium-sized lactones and lactams from linear precursors is described in which an amine acts as an internal nucleophilic catalyst to facilitate a novel cyclisation/ring expansion cascade sequence. This method obviates the need for the high-dilution conditions usually associated with medium-ring cyclisation protocols, as the reactions operate exclusively via kinetically favourable "normal"-sized cyclic transition states. This same feature also enables biaryl-containing medium-sized rings to be prepared with complete atroposelectivity by point-to-axial chirality transfer.

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Enantioselective Synthesis of Medium-Sized Lactams via Chiral α,β-Unsaturated Acylammonium Salts.

Angew Chem Int Ed Engl

May 2018

Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA.

Medium-sized lactams are important structural motifs found in a variety of bioactive compounds and natural products but are challenging to prepare, especially in optically active form. A Michael addition/proton transfer/lactamization organocascade process is described that delivers medium-sized lactams, including azepanones, benzazepinones, azocanones, and benzazocinones, in high enantiopurity through the intermediacy of chiral α,β-unsaturated acylammonium salts. An unexpected indoline synthesis was also uncovered, and the benzazocinone skeleton was transformed into other complex heterocyclic derivatives, including spiroglutarimides, isoquinolinones, and δ-lactones.

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Pinnatifidenyne-Derived Ethynyl Oxirane Acetogenins from Laurencia viridis.

Mar Drugs

December 2017

Instituto Universitario de Bio-Orgánica Antonio González (IUBO AG), Centro de Investigaciones Biomédicas de Canarias (CIBICAN), Universidad de La Laguna (ULL), Avenida Astrofísico Francisco Sánchez 2, 38206 Tenerife, Spain.

Red algae of continue to provide wide structural diversity and complexity of halogenated C acetogenin medium-ring ethers. Here, we described the isolation of three new C acetogenins (-), and one truncated derivative () from collected on the Canary Islands. These compounds are interesting variations on the pinnatifidenyne structure that included the first examples of ethynyl oxirane derivatives (-).

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