(E)-2-(4'-METHYL-3'-PENTENYLIDENE)-4-BUTANOLIDE, NAMED BETA-ACARIOLIDE - A NEW MONOTERPENE LACTONE FROM THE MOLD MITE, TYROPHAGUS-PUTRESCENTIAE (ACARINA, ACARIDAE)

Reinvestigation of the opisthonotal gland secretion of the mold mite, Tyrophagus putrescentiae, resulted in the isolation of a new monoterpe ne lactone, whose chemical structure was elucidated as (E)-2-(4'-methy l-3'-pentenylidene)-4-butanolide (3), to which we gave the trivial nam e beta-acariolide in relation to beta-acaridial {1, (E)-2-(4-methyl-3- pentenylidene)-butanedial}. The compound was synthesized by LiAlH3 (OE t) reduction of 1 and subsequent oxidation involving simultaneous cycl ization by using Ag2CO3 on Celite. Both the E-and Z-isomers of beta-ac ariolide (3 and 4) were also prepared by the reaction of alpha-ethoxal y-gamma-butyrolactone (6) and 4-methyl-3-pentenal under basic conditio ns. Their NMR spectra were compared with each other, and the geometry of the pentenylidene double bond of the isolated compound was conclude d as being E.