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Pigments from the Puffball Calvatia rubro ‐ flava − Isolation, Structural Elucidation and Synthesis
Author(s) -
Fugmann Burkhard,
Arnold Siegbert,
Steglich Wolfgang,
Fleischhauer Jörg,
Repges Charlotte,
Koslowski Axel,
Raabe Gerhard
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200108)2001:16<3097::aid-ejoc3097>3.0.co;2-v
Subject(s) - chemistry , isolation (microbiology) , pigment , organic chemistry , microbiology and biotechnology , biology
The orange pigment rubroflavin ( 1 ) from the dried fruit bodies of Calvatia rubro ‐ flava (Lycoperdaceae) owes its high optical rotation to a methanesulfinyl group directly attached to a 1,4‐benzoquinone semicarbazone chromophore. Rubroflavin is present in fresh fungi in its leuco form 4 , which is easily oxidized to 1 . Thermal fragmentation of 1 yields (−)‐3‐methanesulfinyl‐5‐(methylthio)phenol ( 6 ), whose configuration was assigned as ( S ) by quantum mechanical calculations. This result is supported by CD comparison of 6 with ( S )‐4‐(methanesulfinyl)toluene, and the synthesis of ( S )‐ 1 from esters of deoxyrubroflavin ( 8 ) by stereoselective sulfoxidation. In the same manner, optically active ( S , S )‐oxyrubroflavin ( 2 ) and ( S )‐craniformin ( 3 ) were obtained. NMR measurements in different solvents indicate that 1 and the related 1,4‐benzoquinone semicarbazones are in equilibrium with their azophenol tautomers.