The photochemical behavior of colchicone and thiocolchicone

Year: 2000

Authors: Bussotti L., D\’Auria M., Foggi P., Lesma G., Righini R., Silvani A.

Autors Affiliation: LENS, largo E. Fermi, Firenze, Italy; Dipartimento di Chimica, Università della Basilicata, Potenza, Italy; Dipartimento di Chimica, Università di Perugia, Perugia, Italy; Dipto. di Chim. Organ. e Industriale, Milano, Italy; Dipartimento di Chimica, Università di Firenze, Firenze, Italy; Dipartimento di Chimica, Universitá della Basilicata, Via N. Sauro 85, 85100 Potenza, Italy

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 ß-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 St 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.

Journal/Review: PHOTOCHEMISTRY AND PHOTOBIOLOGY

Volume: 71 (1)      Pages from: 29  to: 34

KeyWords: Alkaloid derivative; beta lumicolchicone; colchicone; thiocolchicone; unclassified drug, absorption spectroscopy; article; calculation; drug synthesis; empiricism; irradiation; isomerism; photochemistry; photoreactivity, Colchicine; Magnetic Resonance Spectroscopy; Photochemistry; Spectrophotometry, Ultraviolet
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