(E)-2-(4′-Methyl-3′-pentenylidene)-4-butanolide, Namedβ-Acariolide: A New Monoterpene Lactone from the Mold Mite,Tyrophagus putrescentiae(Acarina: Acaridae)
(E)-2-(4′-Methyl-3′-pentenylidene)-4-butanolide, Namedβ-Acariolide: A New Monoterpene Lactone from the Mold Mite,Tyrophagus putrescentiae(Acarina: Acaridae)
(<i>E</i>)-2-(4′-Methyl-3′-pentenylidene)-4-butanolide, Named<i>β</i>-Acariolide: A New Monoterpene Lactone from the Mold Mite,<i>Tyrophagus putrescentiae</i>(Acarina: Acaridae)
Reinwestigation of the opisthonotal gland secretion of the mold mite, Tyrophagus putrescentiae, resulted in the isolation of a new monoterpene lactone, whose chemical structure was elucidated as (E)-2-(4′-methyl-3′-pentenylidene)-4-butanolide (3), to which we gave the trivial name β-acariolide in relation to β-acaridial 1, (E)-2-(4-methyl-3-pentenylidene)-butanedial}. The compound was synthesized by LiAlH3 (OEt) reduction of 1 and subsequent oxidation involving simultaneous cyclization by using Ag2CO3 on Celite. Both the E- and Z-isomers of β-acariolide (3 and 4) were also prepared by the reaction of α-ethoxaly-γ-butyrolactone (6) and 4-methyl-3-pentenal under basic conditions. Their NMR spectra were compared with each other, and the geometry of the pentenylidene double bond of the isolated compound was concluded as being E.