The Photochemical Behavior of Colchicone and Thiocolchicone

Laura Bussotti; Maurizio D'Auria; Paolo Foggi; Giordano Lesma; Roberto Righini; Alessandra Silvani

doi:10.1562/0031-8655(2000)071<0029:TPBOCA>2.0.CO;2

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1 January 2000 The Photochemical Behavior of Colchicone and Thiocolchicone

Laura Bussotti, Maurizio D'Auria, Paolo Foggi, Giordano Lesma, Roberto Righini, Alessandra Silvani

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Photochemistry and Photobiology, 71(1):29-34 (2000). https://doi.org/10.1562/0031-8655(2000)071<0029:TPBOCA>2.0.CO;2

Abstract

The irradiation of colchicone 5 led to the formation of lumicolchicone 7. The same reaction cannot be obtained by using thiocolchicone 6 as substrate. Transient absorption spectroscopy of colchicone and β-lumicolchicone showed that probably the photoisomerization occurred on colchicone in its first excited singlet state. The spectroscopic data are in agreement with the hypothesis that lumicolchicone was generated in the ground state from the S₁ state of colchicone without the presence of any intermediate. Semiempirical calculations on colchicone and thiocolchicone showed that the highest single occuped molecular orbital and the lowest unoccupied molecular orbital of the singlet excited colchicone can give a disrotatory ring closure to 7, while thiocolchicone cannot give the same type of process.

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Laura Bussotti, Maurizio D'Auria, Paolo Foggi, Giordano Lesma, Roberto Righini, and Alessandra Silvani "The Photochemical Behavior of Colchicone and Thiocolchicone," Photochemistry and Photobiology 71(1), 29-34, (1 January 2000). https://doi.org/10.1562/0031-8655(2000)071<0029:TPBOCA>2.0.CO;2

Received: 8 July 1999; Accepted: 1 September 1999; Published: 1 January 2000

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