An Unusual Series of Thiomethylated Canthin-6-ones from the North American Mushroom Boletus curtisii

A unique set of thiomethylated canthin‐6‐one derivatives was isolated from Boletus curtisii. The bright yellow color of this mushroom is caused by two optically active canthin‐6‐one sulfoxides for which the names curtisin and 9‐deoxycurtisin are proposed. The structures of the new compounds were established by MS and NMR methods and the absolute configuration of the sulfoxides determined by quantum chemical calculations. This is the first occurrence of canthin‐6‐one alkaloids outside of higher plants. The chemotaxonomic implications of these findings are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)