Thiophanic acid

Lichen xanthonee. Compounds found in numerous lichens that are mostly derived from norlichexanthone (occurring, e. g., in Lecanora straminea). The occurrence of mono-, di-, tri-, and tetrachloroxanthones such as, e.g., thuringione (from Lecidella carpathica) or thiophanic acid (from Lecanora rupicola and numerous other lichens) is remarkable. 

Lecanora rupicola Atranorin Chloroatranorin Roccellic acid Sordidone Thiophanic acid Eugenitin Eugenitol Roccellic acid Sordidone Fox and Huneck (1969)... 

Tetrachlorohypericin Thiomelin Thiophanic acid Thiophaninic acid Thuringione... 

B Thiophanic acid pale yellow narrow lamellae... 

MS, m/z 402 (M%2%), 400 (12), 398 (50), 396 (100), 394 (75), 361 (10), 360 (6), 359 (8), 331 (5) Deriv Tri-O-methylthiophanic acid, cream-coloured needles (CHjClj-MeOH), mp 215-216 °C, from thiophanic acid with CHjNj at room temperature in 3 days. Triacetylthio-phanic acid, cream-coloured needles (CHjClj-MeOH), mp 261-262 °C, from thiophanic acid with AC2O-H2SO4 StL Lecanora rupicola (L.) Zahlbr. 

Santesson J (1968) Chemical studies on lichens. 16. The xanthones of Lecanora straminea. I. Arthothelin and thiophanic acid. Ark Kemi 30 449-454... 

Arshad, M., J. P. Devlin, and W. D. Ollis Synthesis of Sordidone and Thiophanic Acid, Two Chlorine-containing Lichen Metabolites. J. Chem. Soc. (London) C 1971, 1324. 

Santesson, j. Chemical Studies on Lichens. 16. The Xanthones of Lecanora straminea. I. Arthothelin and Thiophanic Acid. Ark. Kemi 30, 449 (1969). 

Examples are thuringion (38) and thiophanic acid (39), which absorbs in UV... 

Condensation of orsellinic acid (40) with phloroglucinol (41) leads to norlichexanthone which can be chlorinated to thiophanic acid (39) with chlorine in acetic acid. 

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