Isolation of a new caryophyllane ester from Lactarius subumbonatus: conformational analysis and absolute configuration

(1R,6R,9S)-6-Hydroxycaryophyllene (S)-6-hydroxystearate, a sesquiterpene alcohol esterified by the unusual fatty acid (S)-(+)-6-hydroxystearic acid, has been isolated from the fruiting bodies of the Basidiomycete Lactanus subumbonatus. Both NMR data and AM1 calculations indicate that the caryophyllene macrocyclic ring adopts a ββ conformation. The absolute configuration of the sesquiterpene moiety has been established by theoretical Circular Dichroism calculations (De Voe coupled oscillators theory) and that of the fatty acid by NMR studies of the (R)-2-methoxy-2-naphthylacetic acid (2-NMA) ester.