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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
A photochemical synthesis of functionalized trans-cyclooctenes driven by metal complexation
Maksim Royzen1, Glenn P A Yap, Joseph M Fox
1Brown Laboratories, Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Abstract:
Described is a scalable procedure for driving photochemical sytheses of trans-cyclooctene derivatives through metal complexation. During photoirradiation, reaction mixtures are continuously pumped through a column of a AgNO3-impregnated silica gel. The trans-cyclooctene derivative is selectively retained by the AgNO3-impregnated silica, but the cis-isomer elutes from the column back to the reaction flask, where it is photoisomerized and recirculated through the column. The method provides access to a range of usefully functionalized derivatives of trans-cyclooctene, including a derivative of 5-aza-trans-cyclooctene that underwent transannular cyclization upon treatment with bromine. The alkene stereochemistry is transferred with high fidelity to the hexahydropyrrolizine framework in the transannular cyclization.
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