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![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Biocatalyzed and Photochemical Formal [2+2] Cycloaddition of Euphoboetirane A: A Route to a Fused Pentacyclic
Fátima Vela Benavides1, Marija Kirić1, Felipe Escobar-Montaño1
1Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Cádiz, Puerto Real, 11510 Cádiz, Spain.
Abstract:
Cycloeuphoboetirane A (2), a new diterpene with an unprecedented pentacyclic skeleton, has been obtained from lathyrane euphoboetirane A (1). A formal intramolecular [2+2] cycloaddition reaction catalyzed by Sordaria tomento-alba ST1-UCA is involved, providing new evidence for the existence of enzymes capable of catalyzing this reaction. A biomimetic photochemical conversion was also achieved by benzophenone with light-emitting diode irradiation.
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Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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