Additional Vinyl Ketones and Their Pyranyl Ketones in Gonyleptid Harvestmen (Arachnida: Opiliones) Suggest These Metabolites Are Widespread in This Family

Four species of gonyleptid harvestmen, <i>Acanthogonyleptes pulcher</i>,<i> Gonyleptes saprophilus</i> (Gonyleptinae), <i>Sodreana barbiellini</i>, and <i>Sodreana leprevosti</i> (Sodreaninae), were examined by GC-MS and ¹H NMR. All of these species release vinyl ketones, and three of them produce the corresponding pyranyl ketones, which are presumed hetero-Diels–Alder (HDA) dimers. The vinyl ketones 5-methyl-1-hexen-3-one, <i>rac</i>-4-methyl-1-hexen-3-one, and (<i>S</i>)-4-methyl-1-hexen-3-one were synthesized. Natural 4-methyl-1-hexen-3-one is present as a single stereoisomer and has the <i>R</i>-configuration. Vinyl ketone dimers (HDA dimers) were also observed in the scent gland exudate and characterized by HRMS, ¹³C NMR, and ¹H NMR chemical shifts of the pyranyl moiety