Synthesis of (+)-9-Demethyl-7,8-dideoxycalopin as a Model for the Determination of the Absolute Stereochemistry of a New Group of Fungal Metabolites

Calopins and Cyclocalopins − Bitter Principles fromBoletus calopus and Related Mushrooms

“…The major component of the extracts from Boletus calopus, B. coniferarum, and B. radicans was O-acetylcalopin (1a), which possesses the molecular formula C 15 H 18 O 6 . From the NMR spectroscopic data (Table 1) and the HMBC correlations, the presence of a 2,3-dihydroxy-4-methylphenyl ring was easily discernible.…”

“…This complemented the conclusions drawn from the negative ∆δ values of the lactone and aryl protons, which placed them on the left-hand side of the MTPA plane. Very similar ∆δ values were obtained with synthetic (2S,3R,4S)-2-hydroxy-4-methyl-3-phenyl-δ-lactone (3), [6] supporting the assignment of absolute configuration established with natural calopin. Interestingly, during the HPLC separation procedure described above, a less polar form of O-acetylcalopin with the same UV spectrum could be detected.…”

Synthesis of the α,β-Unsaturated δ-Lactones (+)-Anhydrocalopin and (+)-Dehydrocalopin

“…They represent a new class of natural products possessing a d-lactone moiety and, in the case of O-acetylcalopin (1a) and calopin (1b) ( Figure 1), a rare methylcatechol residue. 1 The absolute configuration of these metabolites has been determined by synthetic studies 2 including the total synthesis of (+)-1b. 3…”

Neuartige Metaboliten aus dem Schönfuß‐Röhrling und verwandten Bitterpilzen

“…bestätigen. Die gefundenen Calopine stellen eine neue Naturstoffklasse dar [2]. Unter ihnen ist Acetylcyclocalopin A für den bitteren Geschmack verantwortlich.…”

“…Um die absolute Konfiguration sicher zu bestimmen, schlossen Steglich und seine Mitarbeiter den spek-troskopischen Messungen eine Synthese an [2]. Sie ersetzten zunächst die Methylcatechol-Gruppe durch einen Phenyl-Substituenten.…”